Fish go into chippy (9)
I believe the answer is:
carpenter
'chippy' is the definition.
(informal term for a carpenter)
'fish go into' is the wordplay.
'fish' becomes 'carp' (carp is a kind of fish).
'go into' becomes 'enter' (enter can mean to go into a place).
'carp'+'enter'='CARPENTER'
(Other definitions for carpenter that I've seen before include "What Jesus was" , "artisan" , "tradesman" , "Chippy" , "Karen was one" .)