Two items of underwear, most daring (7)
I believe the answer is:
bravest
'most daring' is the definition.
(I've seen this before)
'two items of underwear' is the wordplay.
'two items of' becomes 'bra' (I can't justify this - if you can you should give a lot more credence to this answer).
'underwear' becomes 'vest'.
'bra'+'vest'='BRAVEST'
(Other definitions for bravest that I've seen before include "Most handsome" , "Most valiant" , "Most courageous" , "Most daring" , "Most heroic" .)