Good man, aye, on eye troubles (5)
I believe the answer is:
styes
'eye troubles' is the definition.
(I've seen this in another clue)
'good man aye on' is the wordplay.
'good man' becomes 'st' (abbreviation for saint).
'aye' becomes 'yes' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'st'+'yes'='STYES'
(Other definitions for styes that I've seen before include "Eyelid swellings" , "Problems seeing" , "Eye infections" , "Pig pens" , "Eyesores" .)