Flatten pasture with first cut (4)
I believe the answer is:
raze
'flatten' is the definition.
(raze can mean to destroy or flatten)
'pasture with first cut' is the wordplay.
'pasture' becomes 'graze' (synonyms).
'with first cut' means to remove the first letter.
'graze' with its first letter taken away is 'RAZE'.
(Other definitions for raze that I've seen before include "Burn to the ground" , "Tear down and make flat with the ground" , "level" , "fell" , "Demolish (a building)" .)