Outlaw group on appeal (6)
I believe the answer is:
bandit
'outlaw' is the definition.
(bandit is a kind of outlaw)
'group on appeal' is the wordplay.
'group' becomes 'band' (band can mean a group of people).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'appeal' becomes 'it' ('it' can mean something attractive or appealing).
'band'+'it'='BANDIT'
(Other definitions for bandit that I've seen before include "Violent robber" , "Desperado" , "Member of a robber gang" , "Crook" , "Dan bit the robber badly" .)