Race car leaving front of plant (6)
I believe the answer is:
nation
'race' is the definition.
(both can mean a national or ethnic group)
'car leaving front of plant' is the wordplay.
'leaving front of' indicates named letters should be taken away (letters removed from the front of the word).
'plant' becomes 'carnation' (carnation is a flower).
'carnation' with 'car' removed is 'NATION'.
(Other definitions for nation that I've seen before include "Body of people united by their homeland" , "People sharing a common culture/descent" , "People of common culture or descent" , "Large community of people under one government" , "Anoint (anag)" .)