Fruit, fleshy, reduced (4)
I believe the answer is:
plum
'fruit' is the definition.
(plum is a kind of fruit)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for plum that I've seen before include "Fruit tree - of especial value?" , "Best; fruit" , "First-class - fruit" , "Pudding fruit" , "Brilliant" .)