Emblem, not good, e.g. being rejected (5)
I believe the answer is:
badge
'emblem' is the definition.
(badge is a kind of emblem)
'not good e g being rejected' is the wordplay.
'not good' becomes 'bad' (bad is the opposite of good).
'being rejected' says the letters should be written in reverse.
'e'+'g'='eg'
'eg' backwards is 'ge'.
'bad'+'ge'='BADGE'
(Other definitions for badge that I've seen before include "Symbol worn for identification" , "Emblem of belonging" , "Emblem of office" , "One cheating others with fictitious schemes" , "Worn emblem" .)