Do well with fish: ten about to be netted (5)
I believe the answer is:
excel
'do well' is the definition.
(I've seen this before)
'fish ten about to be netted' is the wordplay.
'fish' becomes 'eel' (eel is a type of fish).
'ten' becomes 'X' (Roman numeral).
'about to be' becomes 'c' (I've seen this in other clues).
'netted' means one lot of letters goes inside another (inserted letters are caught or netted).
'x'+'c'='xc'
'eel' going around 'xc' is 'EXCEL'.
'with' acts as a link.
(Other definitions for excel that I've seen before include "Outrival" , "Do better than, give great performance" , "Be outstandingly proficient" , "well above average" , "Be very good at, better than others" .)