One in vehicle going over any number of stones in a heap (5)
I believe the answer is:
cairn
'stones in a heap' is the definition.
'cairn' can be an answer for 'heap' (I have seen 'Heap of stones' mean 'cairn' so perhaps 'heap' could also mean 'cairn'). I am unsure of the 'stones in a' bit.
'one in vehicle going over any number' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'vehicle' becomes 'car' (car is a kind of vehicle).
'going over' means one lot of letters go next to another.
'any number' becomes 'n' (mathematical symbol for an unspecified number).
'i' put within 'car' is 'cair'.
'cair'+'n'='CAIRN'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for cairn that I've seen before include "dog" , "Stone mound" , "Piled-stone marker" , "Burial place of old" , "Variety of 10" .)