Heartless description of cat causes anger (4)
I believe the answer is:
fury
'anger' is the definition.
(fury is a kind of anger)
'heartless description of cat' is the wordplay.
'heartless' suggests removing the centre.
'description of cat' becomes 'furry'.
'furry' with its middle removed is 'FURY'.
'causes' is the link.
(Other definitions for fury that I've seen before include "Hellcat" , "passionate woman" , "Great anger or rage" , "Fierce temper" , "Violence" .)