Relating to sheep (5)
I believe the answer is:
ovine
'relating to sheep' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ovine that I've seen before include "like a mug" , "Sheep-like" , "1/6 = 2/3 of 28 [SHEEPISH" , "Resembling a sheep" , "Pertaining to sheep" .)