Future leaf (3)
I believe the answer is:
bud
'future leaf' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for bud that I've seen before include "mate in America" , "Opening flower" , "Shoot, sprout" , "Small knob that will develop into a leaf or flower" , "It will eventually become a leaf or flower" .)