Complex sentence: In January 1970 he joined Arsenal for £100,000 (a club record fee and the first time Arsenal had paid a six-figure sum for a player) and he scored on his debut, against Manchester United at Old Trafford on 10 January 1970.
Split into simpler sentences: In January 1970 he joined Arsenal for £100,000, a club record fee at the time. He went on to score on his debut, against Manchester United at Old Trafford on 10 January 1970.