Upset by dad, Enid has that hurt expression (6)
I believe the answer is:
pained
'upset' is the definition.
Both the answer and definition are adjectives. Maybe you can see a link between them that I can't see?
'dad enid has that hurt expression' is the wordplay.
I cannot really see how this works, but
'dad' could be 'pa' (both can mean one's father) and 'pa' is found in the answer.
an anagram of 'enid' is 'ined' which is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'by' acts as a link.
Can you help me to learn more?
(Other definitions for pained that I've seen before include "Hurt and disapproving (6)" , "Distressed and annoyed - hurted" , "Caused hurt." , "Distressed so it hurts?" , "Distressed or hurt in feelings" .)