Small fruit seed (3)
I believe the answer is:
pip
'small fruit seed' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pip that I've seen before include "Defeat at the last moment - . . . at the post" , "Palindromic pear seed" , "Palindromic fruit seed" , "Win (just)" , "Mark of rank" .)