Creeper following Oscar, sheep-like (5)
I believe the answer is:
ovine
'sheep-like' is the definition.
(I've seen this before)
'creeper following oscar' is the wordplay.
'creeper' becomes 'vine' (I've seen this in another clue).
'following' is a charade indicator (letters next to each other).
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'vine' after 'o' is 'OVINE'.
(Other definitions for ovine that I've seen before include "Pertaining to sheep" , "Relating to sheep" , "Sheep-like" , "Like a sheep" , "like a mug" .)