Sharp-witted animal close to fold (6)
I believe the answer is:
shrewd
'sharp-witted' is the definition.
(I've seen this before)
'animal close to fold' is the wordplay.
I cannot quite see how this works, but
'animal' could be 'shrew' (shrew is a kind of animal) and 'shrew' is found within the answer.
A single letter 'd' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for shrewd that I've seen before include "Canny and calculating" , "Sharp-witted" , "Wily" , "Craftily astute" , "Astute, calculating" .)