Robber also breaking into section (6)
I believe the answer is:
bandit
'robber' is the definition.
(thesaurus)
'also breaking into section' is the wordplay.
'also' becomes 'and' (I've seen this before).
'breaking into' is an insertion indicator.
'section' becomes 'bit' (I've seen this in other clues).
'and' inserted within 'bit' is 'BANDIT'.
(Other definitions for bandit that I've seen before include "Outlaw, brigand" , "Armed brigand" , "Thief" , "Highwayman" , "Crook" .)