Reasonable-sounding food (4)
I believe the answer is:
fare
'food' is the definition.
(fare is a kind of food)
'reasonable-sounding' is the wordplay.
'reasonable' becomes 'fair' ('fair' can be a synonym of 'reasonable').
'sounding' shows a homophone (sound like).
'fair' sounds like 'FARE'.
(Other definitions for fare that I've seen before include "Food for the table" , "Price of passage" , "Paying passenger" , "Charge for travelling on train or bus" , "Commons" .)