Daring Charlie's predecessor to capture a duke (7)
I believe the answer is:
bravado
'daring' is the definition.
(I've seen this before)
'charlie's predecessor to capture a duke' is the wordplay.
'charlie's predecessor' becomes 'Bravo' (in the NATO phonetic alphabet).
'to capture' means one lot of letters goes inside another.
'duke' becomes 'd' (abbreviation).
'a'+'d'='ad'
'bravo' going around 'ad' is 'BRAVADO'.
(Other definitions for bravado that I've seen before include "Boastfulness" , "Boastful swagger" , "A show of boldness or bluster" , "Boastful courage" , "Rash display of courage" .)