Clump of grass (4)
I believe the answer is:
tuft
'clump of grass' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tuft that I've seen before include "Sort of undergrad" , "Bunch of threads or hair" , "Small clump (of grass)" , "Bunch of threads or grass" , "Bunch of threads or feathers held together at base" .)