Old horny creature rolling round floor (4)
I believe the answer is:
kayo
'round floor' is the definition.
'kayo' can be an answer for 'floor' (I've seen this before). I'm not certain of the 'round' bit.
'old horny creature rolling' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'horny creature' becomes 'yak' (I have seen 'Tibetan creature' mean 'yak' so perhaps 'creature' could also mean 'yak'. I am not sure about the 'horny' bit.).
'rolling' says the letters should be written backwards.
'o'+'yak'='oyak'
'oyak' backwards is 'KAYO'.
Can you help me to learn more?
(Other definitions for kayo that I've seen before include "KO (sl.)" , "To render senseless" , "Fight's ending" , "floor" , "Decisive end to a fight?" .)