Jack drove van kilometres partly in reverse (5)
I believe the answer is:
knave
'jack' is the definition.
(knave can mean a jack playing card)
'drove van kilometres partly in reverse' is the wordplay.
'partly' says the answer is hidden in the clue (part of the clue is used).
'in reverse' is a reversal indicator.
'evank' can be found hidden inside 'drove van kilometres'.
'evank' backwards is 'KNAVE'.
(Other definitions for knave that I've seen before include "geezer" , "Unscrupulous man; jack" , "pack member?" , "one found amongst thieves" , "Rascal; picture card" .)