Beast all over mum (5)
I believe the answer is:
llama
'beast' is the definition.
(I've seen this before)
'all over mum' is the wordplay.
'over' says the letters should be written backwards.
'mum' becomes 'ma' (ma can mean mother).
'all' reversed gives 'lla'.
'lla'+'ma'='LLAMA'
(Other definitions for llama that I've seen before include "mammal that chews cud" , "Load-carrier" , "This could carry your stuff" , "South American transport system" , "wool supplier" .)