Face a girl and a wise man (6)
I believe the answer is:
visage
'face' is the definition.
(I know that visage is a type of face)
'a girl and a wise man' is the wordplay.
'a girl' becomes 'vi' (short for Violet).
'and' says to put letters next to each other.
'a wise man' becomes 'sage' (sage is a kind of wise man).
'vi'+'sage'='VISAGE'
(Other definitions for visage that I've seen before include "Clock" , "Face, aspect" , "A person's face, countenance" , "Mug" .)