Animal the cat and sheep retreated from (6)
I believe the answer is:
marmot
'animal' is the definition.
(marmot is a kind of animal)
'the cat and sheep retreated from' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'from' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
The remaining letters 'marm' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for marmot that I've seen before include "wild rodent" , "Coarse-furred burrowing rodent" , "Small burrowing animal of the squirrel family" , "Large burrowing rodent" , "Stout, burrowing rodent" .)