Fruit couple heard of (4)
I believe the answer is:
pear
'fruit' is the definition.
(I know that pear is a fruit)
'couple heard of' is the wordplay.
'couple' becomes 'pair' (synonyms).
'heard of' indicates a 'sounds like' (homophone) clue.
'pair' sounds like 'PEAR'.
(Other definitions for pear that I've seen before include "Pomaceous fruit" , "A fruit; sounds like couple" , "Cider-making fruit" , "Brilliant" , "Fruit related to apple" .)