Bachelor, reckless, insolent (5)
I believe the answer is:
brash
'insolent' is the definition.
(thesaurus)
'bachelor reckless' is the wordplay.
'bachelor' becomes 'b' (abbreviation e.g. BA=Bachelor of Arts).
'reckless' becomes 'rash' ('rash' can be a synonym of 'reckless').
'b'+'rash'='BRASH'
(Other definitions for brash that I've seen before include "Cocksure" , "Impertinent" , "Crudely showy; bumptious" , "Very loud, flashy or showy" , "Tasteless in appearance" .)