OK about the Spanish cat (6)
I believe the answer is:
feline
'cat' is the definition.
(I've seen this before)
'ok about the spanish' is the wordplay.
'ok' becomes 'fine' (synonyms).
'about' is an insertion indicator.
'the spanish' becomes 'el' ('the' in Spanish).
'fine' enclosing 'el' is 'FELINE'.
(Other definitions for feline that I've seen before include "Persian for one" , "An animal of the cat family" , "Like a cat" , "Like a leopard, say" , "16 [TOM] perhaps" .)