Trade vehicle with power door (9)
I believe the answer is:
carpentry
'trade' is the definition.
(I know that carpentry is a type of trade)
'vehicle with power door' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'with' is a charade indicator (letters next to each other).
'power' becomes 'p' (symbol in physics).
'door' becomes 'entry' (synonyms).
'car'+'p'+'entry'='CARPENTRY'
(Other definitions for carpentry that I've seen before include "Woodwork" , "Joining work" , "Trade" , "Craft of a woodworker" , "The purpose of chips" .)