A closure for a container, comprising: - an actuatable portion (800, 900, 1300, 1500, 1700, 1900), said actuatable portion comprising an axially actuatable inner portion, said inner portion is provided with a lower edge, and said inner portion having a sealing member for restricting a fluid flow through a centre of the closure with the inner portion in a first position, wherein the actuatable portion (800, 900, 1300, 1500, 1700, 1900) further comprises: - an outer portion connectable to an opening of the container, said outer portion is provided with an upper edge; - an annular membrane (110, 1310, 1510, 1710, 1910) connecting the upper edge of the outer portion and the lower edge of the inner portion, the closure allowing fluid flow through the centre of the closure with the inner portion in a second position axially displaced relative to the outer portion and where the second position is closer to the container; characterised in that the actuatable portion comprises a structurally weakened annular region (804, 1304a, 1304b, 1504a, 1704, 1904a, 1904b) provided on the annular membrane (110, 1310, 1510, 1710, 1910) on or adjacent to the upper edge of the outer portion, or on or adjacent to the lower edge of the inner portion, such that the closure is configured to provide a returning force to resiliently bias the inner portion towards the first position such that the returning force is lower with the inner portion located at the second position relative to the first position. - an actuatable portion (800, 900, 1300, 1500, 1700, 1900), said actuatable portion comprising an axially actuatable inner portion, said inner portion is provided with a lower edge, and said inner portion having a sealing member for restricting a fluid flow through a centre of the closure with the inner portion in a first position, wherein the actuatable portion (800, 900, 1300, 1500, 1700, 1900) further comprises: - an outer portion connectable to an opening of the container, said outer portion is provided with an upper edge; - an annular membrane (110, 1310, 1510, 1710, 1910) connecting the upper edge of the outer portion and the lower edge of the inner portion, the closure allowing fluid flow through the centre of the closure with the inner portion in a second position axially displaced relative to the outer portion and where the second position is closer to the container; characterised in that the actuatable portion comprises a structurally weakened annular region (804, 1304a, 1304b, 1504a, 1704, 1904a, 1904b) provided on the annular membrane (110, 1310, 1510, 1710, 1910) on or adjacent to the upper edge of the outer portion, or on or adjacent to the lower edge of the inner portion, such that the closure is configured to provide a returning force to resiliently bias the inner portion towards the first position such that the returning force is lower with the inner portion located at the second position relative to the first position. - an outer portion connectable to an opening of the container, said outer portion is provided with an upper edge; - an annular membrane (110, 1310, 1510, 1710, 1910) connecting the upper edge of the outer portion and the lower edge of the inner portion, the closure allowing fluid flow through the centre of the closure with the inner portion in a second position axially displaced relative to the outer portion and where the second position is closer to the container; characterised in that