Slope initially dropped a shade (5)
I believe the answer is:
amber
'a shade' is the definition.
(I know that amber is a type of shade)
'slope initially dropped' is the wordplay.
'slope' becomes 'camber' (camber is a kind of slope).
'initially dropped' means to remove the first letter.
'camber' with its first letter taken off is 'AMBER'.
(Other definitions for amber that I've seen before include "The traffic-light between red and green" , "Prepare-to-stop signal" , "Stone" , "Cautionary light" , "gives warning" .)