I have to entertain daughter absolutely (6)
I believe the answer is:
indeed
'absolutely' is the definition.
(both can be used to agree with something)
'i have to entertain daughter' is the wordplay.
'have' becomes 'need' (synonyms).
'to entertain' means one lot of letters goes inside another.
'daughter' becomes 'd' (genealogical abbreviation).
'need' going around 'd' is 'ndeed'.
'i'+'ndeed'='INDEED'
(Other definitions for indeed that I've seen before include "In truth, in fact" , "even" , "beyond doubt" , "Absolutely" , "Really - truly" .)