Check grass brought round for ruminant (8)
I believe the answer is:
reindeer
'for ruminant' is the definition.
(reindeer is a kind of ruminant)
'check grass' is the wordplay.
'check' becomes 'rein' (both can mean to control or limit).
'grass' becomes 'deer' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rein'+'deer'='REINDEER'
'brought round' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for reindeer that I've seen before include "Rudolph, for instance" , "Arctic ungulate" , "Eg, Prancer and Dancer" , "Northern ungulate" , "Christmas card creatures" .)