Trim the grass (3)
I believe the answer is:
mow
'trim the grass' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mow that I've seen before include "'Cut, grass say (3)'" , "Cut (e.g. grass)" , "Cut grass or grain" , "'Cut down, hay, say (3)'" , "Scythe" .)