Nascent flower (3)
I believe the answer is:
bud
'nascent flower' 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 "Small pre-flower knob - nip it" , "Flower yet to open" , "Opening flower" , "Tight flower" , "It will eventually become a leaf or flower" .)