Drink father upset in dismay (5)
I believe the answer is:
appal
'dismay' is the definition.
(synonyms)
'drink father upset' is the wordplay.
'drink' becomes 'lap' (lap can mean to drink).
'father' becomes 'pa' (pa can mean dad or father).
'upset' says the letters should be written in reverse.
'lap'+'pa'='lappa'
'lappa' back-to-front is 'APPAL'.
'in' acts as a link.
(Other definitions for appal that I've seen before include "Greatly dismay" , "Disgust" , "Petrify" , "expressed dismay" , "Put at rest (suspicion)" .)