Swindled daughter? Was not greatly exercised about daughter (7)
I believe the answer is:
diddled
'swindled' is the definition.
('diddle' can be a synonym of 'swindle')
'greatly exercised about daughter' is the wordplay.
'greatly' becomes 'eld' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'exercised' becomes 'did' ('do' can be a synonym of 'exercise').
'about' says the letters should be written backwards.
'daughter' becomes 'd'.
'eld'+'did'='elddid'
'elddid' reversed gives 'diddle'.
'diddle'+'d'='DIDDLED'
'daughter? was not' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for diddled that I've seen before include "Swindled" , "cheated" .)