Sounds moderately good grub (4)
I believe the answer is:
fare
'grub' is the definition.
(I've seen this in another clue)
'sounds moderately good' is the wordplay.
'sounds' shows a homophone (sound like).
'moderately good' becomes 'fair' (I've seen this before).
'fair' is a homophone of 'FARE'.
(Other definitions for fare that I've seen before include "Taxi charge; food" , "Paying passenger" , "Food for the table" , "Amount charged" , "what the commuter will pay" .)