Fish work for slattern? (7)
I believe the answer is:
trollop
'slattern?' is the definition.
(slattern is a kind of trollop)
'fish work' is the wordplay.
'fish' becomes 'troll' (trolling is a type of fishing).
'work' becomes 'op' (abbreviation for opus).
'troll'+'op'='TROLLOP'
'for' acts as a link.
(Other definitions for trollop that I've seen before include "Disreputable woman" , "Lady of easy virtue" , "Pro" , "Drab" , "person of dubious morality" .)