Petrol store for vehicle (4)
I believe the answer is:
tank
This clue might be a double definition.
'petrol store' is the first definition.
'tank' can be an answer for 'store' (thesaurus). I'm not sure about the 'petrol' bit.
'vehicle' is the second definition.
(tank is a kind of vehicle)
'for' acts as a link.
Can you help me to learn more?
(Other definitions for tank that I've seen before include "Large container for liquid" , "Possible alternative to barrel" , "Car fuel container" , "Storage chamber; drink heavily (colloq.)" , "Armoured vehicle; large container" .)