A daughter enthralled by hired killer's swagger (7)
I believe the answer is:
bravado
'swagger' is the definition.
(I've seen this before)
'a daughter enthralled by hired killer's' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'enthralled by' is an insertion indicator ('enthral' can mean 'capture').
'hired killer' becomes 'bravo' (historical type of assassin in Italy).
'a'+'d'='ad'
'ad' inserted inside 'bravo' is 'BRAVADO'.
(Other definitions for bravado that I've seen before include "Impressive boldness" , "Daring to impress" , "Boastful threatening" , "Boastfulness" , "Unjustified assertion of confidence" .)