Allows a change of complexion (6)
I believe the answer is:
sallow
'complexion' is the definition.
(I have seen 'Sickly complexion ' mean 'sallow' so perhaps 'complexion' could also mean 'sallow')
'allows a change' is the wordplay.
'a change' indicates an anagram.
'allows' anagrammed gives 'SALLOW'.
'of' is the link.
(Other definitions for sallow that I've seen before include "Pale; sickly" , "(Of complexion) pale and unhealthy" , "Unhealthy-looking" , "Pale yellowish complexion, often through poor health" , "Pasty-faced" .)