Complex sentence: In April 2013, Allan became the youngest player to represent a first team in Scotland at the age of 14 years and 199 days, making his debut for Airdrie against Livingston in a 2-0 defeat.
Split into simpler sentences: In April 2013, Allan became the youngest player to represent a first team in Scotland at the age of 14 years and 199 days. He made his debut for Airdrie against Livingston in a 2-0 defeat.