Grass some ruminants pulled up (4)
I believe the answer is:
reed
'grass' is the definition.
(type of grass plant)
'some ruminants pulled up' is the wordplay.
'some ruminants' becomes 'deer' (deer are a type of ruminant).
'pulled up' is a reversal indicator.
'deer' in reverse letter order is 'REED'.
(Other definitions for reed that I've seen before include "Plant of marshy land" , "Vibrating part of some instruments" , "Music pipe" , "Riverside grass" , "Marsh or water plant" .)