He goes in, but is often "on strike" (7)
I believe the answer is:
batsman
'he goes in but is often on strike' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he goes in but is often on' is the wordplay.
I cannot really understand how this works, but
'he' could be 'man' (I've seen this in another clue) and 'man' is found in the answer.
'on' could be 'at' (I've seen this in other clues) and 'at' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for batsman that I've seen before include "one of two on the field" , "He's either in or he's out!" , "Cricketer at the crease" , "Hitting ballplayer" , "Grace, for example" .)