Regret accommodating daughter that’s insolent (4)
I believe the answer is:
rude
'insolent' is the definition.
(thesaurus)
'regret accommodating daughter' is the wordplay.
'regret' becomes 'rue' ('rue' can be a synonym of 'regret').
'accommodating' means one lot of letters goes inside another.
'daughter' becomes 'd'.
'rue' placed around 'd' is 'RUDE'.
'that's' is the link.
(Other definitions for rude that I've seen before include "Ill-mannered; hearty" , "Impertinent" , "'Bad-mannered, discourteous (4)'" , "Coarse or discourteous" , "Impolite, without consideration" .)