Fellow with good old fruit (5)
I believe the answer is:
mango
'fruit' is the definition.
(type of fruit)
'fellow with good old' is the wordplay.
'fellow with' becomes 'man' (I've seen this in other clues).
'good' becomes 'g' (abbreviation).
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'man'+'g'+'o'='MANGO'
(Other definitions for mango that I've seen before include "fruit tree" , "Fleshy tropical fruit" , "Asian fruit" , "fruit-tree" , "Large oval tropical fruit" .)