Bachelor party's daring (5)
I believe the answer is:
brave
'daring' is the definition.
(thesaurus)
'bachelor party's' is the wordplay.
'bachelor' becomes 'b' (abbreviation e.g. BA=Bachelor of Arts).
'party' becomes 'rave' (I've seen this before).
'b'+'rave'='BRAVE'
(Other definitions for brave that I've seen before include "Daring" , "Intrepid and fearless" , "Heroic, valiant" , "Courageous, dauntless" , "Defy" .)