Frost on case of satire gets gruff (6)
I believe the answer is:
hoarse
'gruff' is the definition.
('hoarse' can be a synonym of 'gruff')
'frost on case of satire' is the wordplay.
'frost' becomes 'hoar' ('hoar' can be a synonym of 'frost').
'on' is a charade indicator (letters next to each other).
'case of' suggests removing the centre (outsides of).
'satire' with its middle taken out is 'se'.
'hoar'+'se'='HOARSE'
'gets' acts as a link.
(Other definitions for hoarse that I've seen before include "Of voice, rasping or gruff" , "(Of voice) rough/harsh" , "Having a frog" , "Harsh - throaty" , "Raucous" .)