Reckless forward, first to be dismissed (4)
I believe the answer is:
rash
'reckless' is the definition.
(I know that reckless can be written as rash)
'forward first to be dismissed' is the wordplay.
'forward' becomes 'brash' (both can mean confident or arrogant).
'first to be dismissed' means to remove the first letter.
'brash' with its initial letter taken off is 'RASH'.
(Other definitions for rash that I've seen before include "Foolhardy about the skin infection" , "Impulsive - skin condition" , "Hives" , "Daredevil" , "Lacking in caution" .)