Silent, it follows the cat back (5)
I believe the answer is:
tacit
'silent' is the definition.
('tacit' can be a synonym of 'silent')
'it follows the cat back' is the wordplay.
'follows' says to put letters next to each other.
'back' shows that the letters should be reversed in order.
'cat' back-to-front is 'tac'.
'it' after 'tac' is 'TACIT'.
(Other definitions for tacit that I've seen before include "Implied, unstated" , "Implied without being stated" , "Understood without being directly expressed" , "Implied or understood, not put into words" , "Wordless" .)