Face a little girl and a wise old man (6)
I believe the answer is:
visage
'face' is the definition.
(I know that visage is a type of face)
'a little girl and a wise old man' is the wordplay.
'a little' means to remove the last letter (the word is not quite complete).
'girl' becomes 'viv' (short for Vivienne).
'and' is a charade indicator (letters next to each other).
'a wise old man' becomes 'sage' (I can't justify this - if you can you should give a lot more credence to this answer).
'viv' with its final letter taken off is 'vi'.
'vi'+'sage'='VISAGE'
Can you help me to learn more?
(Other definitions for visage that I've seen before include "Mug" , "Clock" , "Face, aspect" , "A person's face, countenance" .)