As a father, have to look disapproving (5)
I believe the answer is:
frown
'as' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'a father have to look disapproving' is the wordplay.
I cannot quite see how this works, but
'father' could be 'fr' (abbreviation as in a priest's title) and 'fr' is found in the answer.
'have' could be 'own' (to have something is to own it) and 'own' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for frown that I've seen before include "Furrow one's brows" , "Furrow one's brow" , "Disapproving look" , "Scowl, look crossly" , "Facial expression of displeasure" .)