Question: Which city's southern suburbs were the location of an electoral district which lost Labor-voting areas to Victoria Park, Canning and Welshpool, and became substantially safer for the major political party in Australia founded in 1945?

Context paragraphs:
Hambantota Electoral District (1947–1960): Hambantota electoral district was an electoral district of Sri Lanka between August 1947 and March 1960.  The district was named after the city of Hambantota in Hambantota District, Southern Province.  The 1978 Constitution of Sri Lanka introduced the proportional representation electoral system for electing members of Parliament.  The existing 160 mainly single-member electoral districts were replaced with 22 multi-member electoral districts. Hambantota electoral district was replaced by the Hambantota multi-member electoral district at the 1989 general elections, the first under the PR system, though Hambantota continues to be a polling division of the multi-member electoral district.

Victoria Park bus station: Victoria Park bus station, known officially as the Victoria Park Transfer Station, is a Transperth bus station in Victoria Park, Western Australia.  It is located at the eastern end of The Causeway, under the bridge carrying the Great Eastern Highway and Canning Highway.  It has six stands and is served by 30 Transperth routes operated by Path Transit, Swan Transit and Transdev WA.

Electoral district of Queenborough: The Electoral district of Queenborough was an electoral district of the Tasmanian House of Assembly.  It was based in the southern suburbs of Tasmania's capital city, Hobart, in particular Sandy Bay, and surrounding districts such as Cascades, Taroona and Kingston.

Riding association: In Canadian politics, a riding association (French: "association de comté" ), also known as a constituency association and officially called an electoral district association (French: "association de circonscription" ) is the basic unit of a political party, that is it is the party's organization at the level of the electoral district, or "riding".  Major political parties attempt to have a riding association in each constituency though, usually, these associations are more active in ridings where the party has an elected Member of Parliament or has a reasonable chance of electing an MP in the future, and less active in ridings where the party's prospects have historically been poor.

Matara Electoral District (1947–1989): Matara electoral district was an electoral district of Sri Lanka between August 1947 and February 1989.  The district was named after the city of Matara in Matara District, Southern Province.  The 1978 Constitution of Sri Lanka introduced the proportional representation electoral system for electing members of Parliament.  The existing 160 mainly single-member electoral districts were replaced with 22 multi-member electoral districts. Matara electoral district was replaced by the Matara multi-member electoral district at the 1989 general elections, the first under the proportional representation system, Matara continues to be a polling division of the multi-member electoral district.

Electoral district of Clontarf: Clontarf was an electoral district of the Legislative Assembly in the Australian state of Western Australia from 1968 to 1989.  It was located in the southern suburbs of Perth on the Canning River, including such suburbs as Wilson, Bentley, Karawara, Rossmoyne and Shelley.  It was a marginal seat but with progressive redistributions lost Labor-voting areas to Victoria Park, Canning and Welshpool, and became substantially safer for the Liberal Party.

Electoral district of Victoria Park: The Electoral district of Victoria Park is a Legislative Assembly electorate in the state of Western Australia.  Victoria Park is named for the inner southeastern Perth suburb of Victoria Park which falls within its borders.

Electoral district of Heysen: Heysen is an electoral district of the House of Assembly in the Australian state of South Australia.  It is named after Sir Hans Heysen, a prominent South Australian landscape artist.  It is a 1,102 km² electoral district that takes in some of the outer southern suburbs of Adelaide before fanning south-east to include most of the Adelaide Hills, as well as farming areas some distance from the capital.  It includes the areas of Aldgate, Bridgewater, Echunga, Hahndorf, Macclesfield, Meadows, Stirling and Strathalbyn, as well as part of Mount Barker.  Although geographically it is a hybrid urban-rural seat, it is counted as a metropolitan seat.

Liberal Party of Australia: The Liberal Party of Australia is a major political party in Australia.  Founded in 1945 to replace the United Australia Party (UAP), the broadly centre-right Liberal Party is one of the two major parties in Australian politics, along with the Australian Labor Party (ALP).

Electoral district of Canning: The Electoral district of Canning was an electorate in the state of Western Australia.  The electorate, which was named for the Canning River which ran through the electorate, was first contested at the 1897 election, but was abolished prior to the 1901 election, with most of its territory transferred to the new seat of South Perth.  However, for the 1904 election, South Perth was abolished and Canning re-created.  Canning was abolished for a second time in the 1988 redistribution.

Supporting paragraphs: Electoral district of Clontarf Liberal Party of Australia
Answer: Perth