European work accepted by fat cat (7)
I believe the answer is:
leopard
'cat' is the definition.
(I know that leopard is a type of cat)
'european work accepted by fat' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'work' becomes 'op' (abbreviation for opus).
'accepted by' is an insertion indicator (inserted letters are accepted).
'fat' becomes 'lard' (lard is a kind of fat).
'e'+'op'='eop'
'eop' placed within 'lard' is 'LEOPARD'.
(Other definitions for leopard that I've seen before include "Animal that doesn't change its spots" , "Spotted animal" , "Spotted feline" , "dangerous when free" , "Spotted big cat" .)