Whifflet, Lanarkshire born outside right Billy Clark began his football career with Strathclyde and Cambuslang Hibernian, from where he signed for Scottish League club Port Glasgow Athletic in 1901. He scored 18 goals in 60 appearances over three seasons for The Undertakers before being signed by Southern League club Bristol Rovers in the 1904 close season. Clark won The Southern League Championship in his first season with The Gas, still the club’s greatest honour. During his time at Bristol Rovers, Clark played in one Home Scots v Anglo Scots international trial in 1908 but never gained a full cap for Scotland. He went on to make 133 League appearances for Bristol Rovers, scoring 35 goals, before signing for First Division club Sunderland in May 1908.
He made his Football League debut at Manchester City that September but lost his place after five matches and didn’t reclaim his place until the following March as Sunderland finished third in the League Championship. He appeared more regularly during 1909-10 and from February 1910 he played mainly at inside right, but he left The Wearsiders in October 1910 to return to Bristol, this time joining Bristol City, having scored 4 goals in 44 appearances for Sunderland.
He scored just once in 25 matches for The Robins, but they were relegated from the First Division at the end of the 1910-11 season. Clark moved to Second Division club Leicester Fosse in June 1911, but featured in only 6 matches during the first half of The Fossils’ 1911-12 campaign, scoring once, and Leicester was his last known club before his eventual retirement.