Dad's upset, having little enthusiasm (8)
I believe the answer is:
appetite
'enthusiasm' is the definition.
(thesaurus)
'dad's upset having little' is the wordplay.
'dad' becomes 'pa' ('pa' can be a synonym of 'dad').
'upset' says the letters should be written backwards.
'having' is a charade indicator (letters next to each other).
'little' becomes 'petite' ('petite' can be similar in meaning to 'little'**).
'pa' reversed gives 'ap'.
'ap'+'petite'='APPETITE'
(Other definitions for appetite that I've seen before include "Desire, inclination" , "thirst" , "Physical need for food" , "Hunger or zeal" , "Natural craving" .)