Red vehicle goes to one of the pits (7)
I believe the answer is:
carmine
'red' is the definition.
(I know that red can be written as carmine)
'vehicle goes to one of the pits' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'goes to' is a charade indicator (letters next to each other).
'one of the pits' becomes 'mine' (I can't justify this - if you can you should give a lot more credence to this answer).
'car'+'mine'='CARMINE'
Can you help me to learn more?
(Other definitions for carmine that I've seen before include "Vivid red colour" , "Crimson pigment" , "Bright red" .)