Car plant (5)
I believe the answer is:
lotus
I believe this clue is a double definition.
'car' is the first definition.
(I've seen this before)
'plant' is the second definition.
(lotus is a kind of plant)
(Other definitions for lotus that I've seen before include "In Greek mythology, a fruit which induces forgetfulness" , "Large water lily" , "Type of water lily" , "British sports and racing car manufacturer" , "We forget having eaten this" .)