Plant left one at the close to seal a victory (8)
I believe the answer is:
lavender
'plant' is the definition.
The answer is an example.
'left one at the close to seal a victory' is the wordplay.
'left' becomes 'l' (common abbreviation).
'one at the close' becomes 'ender' (someone ending or closing something).
'to seal' indicates putting letters inside.
'victory' becomes 'v'.
'l'+'ender'='lender'
'a'+'v'='av'
'lender' going around 'av' is 'LAVENDER'.
(Other definitions for lavender that I've seen before include "Mauve flower, cultivated for its fragrant oil" , "shade" , "Aromatic shrub related to mint" , "Light bluish-purple" , "Shrub with fragrant purple flowers, used to scent linen" .)