Spot star (3)
I believe the answer is:
pip
I believe this clue is a double definition.
'spot' is the first definition.
(both can mean a small amount)
'star' is the second definition.
(star on a military uniform)
(Other definitions for pip that I've seen before include "Palindromic fruit seed" , "Dickensian hero" , "Greenwich time signal" , "Small hard seed" , "tiny bit of fruit" .)