Two vehicles flanking a travelling group (7)
I believe the answer is:
caravan
'a travelling group' is the definition.
(I've seen this before)
'two vehicles' is the wordplay.
'two vehicles' means two substitutions for 'vehicle'.
'vehicle' becomes 'cara' (I can't explain this - if you can you should give a lot more credence to this answer).
'vehicle' becomes 'van' (van is a kind of vehicle).
'cara'+'van'='CARAVAN'
'flanking' acts as a link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for caravan that I've seen before include "Group crossing a desert" , "Desert convoy" , "Home on wheels" , "Towed vehicle" , "House on wheels" .)