Answer
In February 1961, Clough was on the verge of a move to Arsenal. The deal had been agreed and he had even visited Highbury to meet his new teammates. However, on 18 February, in a First Division match against Bury, Clough injured his knee, after colliding with goalkeeper Harry Gregg. The injury was so severe that Clough was forced to retire from professional football. He was just 23 years old.