Redhead leaving gloss to fade away (6)
I believe the answer is:
vanish
'fade away' is the definition.
(thesaurus)
'redhead leaving gloss' is the wordplay.
'redhead' becomes 'r' (the head/first letter of 'red').
'leaving' indicates named letters should be taken away.
'gloss' becomes 'varnish' (I've seen this before).
'varnish' with 'r' taken out is 'VANISH'.
'to' acts as a link.
(Other definitions for vanish that I've seen before include "make go" , "Become invisible" , "Disappear or fade from sight" , "Evanesce" , "Disappear suddenly" .)