Limits fish caught by ship (5)
I believe the answer is:
sides
'limits' is the definition.
The answer and definition can be both locations as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
'fish caught by ship' is the wordplay.
'fish' becomes 'ide' (type of fish).
'caught by' indicates putting letters inside.
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'ide' put within 'ss' is 'SIDES'.
Can you help me to learn more?
(Other definitions for sides that I've seen before include "opponents?" , "Borders?" , "Flanks, or opposing teams" , "Teams or flat surfaces" , "Sports teams" .)