Sun, fantastic, brings comfort (6)
I believe the answer is:
solace
'comfort' is the definition.
(solace is a kind of comfort)
'sun fantastic' is the wordplay.
'sun' becomes 'sol' (Latin for 'sun').
'fantastic' becomes 'ace' (ace can informally mean very good).
'sol'+'ace'='SOLACE'
'brings' is the link.
(Other definitions for solace that I've seen before include "Kind of comfort - a close thing" , "Comfort in time of disappointment or sorrow" , "Comfort at a time of sadness" , "Relief in affliction" , "Comfort and reassurance" .)