Robber, outlawed we hear, one time (6)
I believe the answer is:
bandit
'robber' is the definition.
(thesaurus)
'outlawed we hear one time' is the wordplay.
'outlawed' becomes 'banned' (banning is a kind of outlawing).
'we hear' shows a homophone (sound like).
'one' becomes 'i' (Roman numeral).
'time' becomes 't'.
'banned' sounds like 'band'.
'band'+'i'+'t'='BANDIT'
(Other definitions for bandit that I've seen before include "hood" , "Highwayman" , "Desperado" , "Dan bit the robber badly" , "(One-armed?) outlaw" .)