... top catch? About 90 (5)
I believe the answer is:
excel
'top' is the definition.
(thesaurus)
'catch? about 90' is the wordplay.
'catch?' becomes 'eel' (potentially makes up a fisherman's catch).
'about' is an insertion indicator.
'90' becomes 'xc' ('xc' can be a synonym of '90').
'eel' placed around 'xc' is 'EXCEL'.
(Other definitions for excel that I've seen before include "Perform exceptionally well" , "Show brilliance" , "Be very good at, better than others" , "Perform extremely well" , "Do better than, give great performance" .)