Animal giving a growl during certain measures (6)
I believe the answer is:
'animal' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ferret that I've seen before include "silk ribbon", "It digs out rabbits", "Jill perhaps", "Kind of weasel, a rabbit hunter", "Type of polecat -- or silk binding tape".)