Wretched dad at home with bad flu (7)
I believe the answer is:
painful
'wretched' is the definition.
(I've seen this before)
'dad at home with bad flu' is the wordplay.
'dad' becomes 'pa' (both can mean one's father).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'with' is a charade indicator (letters next to each other).
'bad' indicates an anagram.
'flu' is an anagram of 'ful'.
'pa'+'in'+'ful'='PAINFUL'
(Other definitions for painful that I've seen before include "Causing physical discomfort" , "Aching, hurtful" , "Embarrassing" , "Causing trouble or difficulty - it hurts" , "Tender" .)