Male resists changing fancy woman (8)
I believe the answer is:
mistress
'fancy woman' is the definition.
(synonyms)
'male resists changing' is the wordplay.
'male' becomes 'm' (common abbreviation).
'changing' indicates anagramming the letters.
'resists' anagrammed gives 'istress'.
'm'+'istress'='MISTRESS'
(Other definitions for mistress that I've seen before include "Female teacher" , "Bit on the side" , "Female owner of a dog" , "Husband's paramour" , "lover" .)