Jaguars, say, reversing a little fast accidentally (4)
I believe the answer is:
cats
'jaguars say' is the definition.
(jaguar is a kind of cat)
'reversing a little fast accidentally' is the wordplay.
'reversing' is a reversal indicator.
'a little' indicates the answer is hidden within the clue.
'stac' is hidden within 'fast accidentally'.
'stac' written backwards gives 'CATS'.
(Other definitions for cats that I've seen before include "Show" , "Siamese, Persian etc" , "Popular musical" , "Feline musical by Andrew Lloyd Webber" , "1981 Lloyd Webber musical" .)