Imitation gem left in delicate shade (6)
I believe the answer is:
pastel
'delicate shade' is the definition.
(I've seen this before)
'imitation gem left' is the wordplay.
'imitation gem' becomes 'paste' (I've seen this in another clue).
'left' becomes 'l' (common abbreviation).
'paste'+'l'='PASTEL'
'in' acts as a link.
(Other definitions for pastel that I've seen before include "Crayon used in art" , "Type of crayon" , "Outmoded" , "Chalky crayon" , "Pleats of a light colour" .)