Catch a right during the fight (5)
I believe the answer is:
sprat
'catch' is the definition.
(sprat is a kind of fish)
'a right during the fight' is the wordplay.
'a right' becomes 'r' (common abbreviation).
'during' is an insertion indicator.
'the fight' becomes 'spat'.
'r' placed within 'spat' is 'SPRAT'.
(Other definitions for sprat that I've seen before include "Young herring" , "Tiny fish" , "Small herring-type fish" , "Small herring, often smoked or canned" , "It's set to catch a mackerel" .)