Robber in group seizing truck (7)
I believe the answer is:
brigand
'robber' is the definition.
(I've seen this in another clue)
'group seizing truck' is the wordplay.
'group' becomes 'band' (band can mean a group of people).
'seizing' indicates putting letters inside (inserted letters are seized).
'truck' becomes 'rig' (I've seen this in another clue).
'band' placed around 'rig' is 'BRIGAND'.
'in' is the link.
(Other definitions for brigand that I've seen before include "Country robber" , "Freebooter" , "Marauder" , "Robber in a gang" , "thief" .)