If possible, good fruit (3)
I believe the answer is:
fig
'fruit' is the definition.
(I know that fig is a type of edible fruit)
'if possible good' is the wordplay.
'if possible' becomes 'fi' (I can't justify this - if you can you should believe this answer much more).
'good' becomes 'g' (abbreviation).
'fi'+'g'='FIG'
Can you help me to learn more?
(Other definitions for fig that I've seen before include "Tree whose leaf may cover nudity" , "Sweet fleshy fruit, often dried" , "Fruit full of tiny seeds" , "Fruit with lots of seeds" , "something unimportant" .)