Book reckless forward (5)
I believe the answer is:
brash
'forward' is the definition.
(both can mean confident or arrogant)
'book reckless' is the wordplay.
'book' becomes 'b' (abbreviation for book).
'reckless' becomes 'rash' (synonyms).
'b'+'rash'='BRASH'
(Other definitions for brash that I've seen before include "Audacious" , "Annoyingly self-assertive" , "Cocksure" , "Vulgarly self-assertive, impudent" , "Offensively loud" .)