Overheard, retailer is more repulsive (7)
I believe the answer is:
grosser
'more repulsive' is the definition.
(I've seen this in another clue)
'overheard retailer' is the wordplay.
'overheard' shows a homophone (sound like).
'retailer' becomes 'grocer' (I've seen this before).
'grocer' sounds like 'GROSSER'.
'is' acts as a link.
(Other definitions for grosser that I've seen before include "More corpulent" , "more vulgar" .)