Thin; slope (4)
I believe the answer is:
lean
I believe this clue is a double definition.
'thin' is the first definition.
(associated in meaning)
'slope' is the second definition.
(I've seen this in another clue)
(Other definitions for lean that I've seen before include "Unproductive" , "Slender" , "Without excess flesh" , "Slight - incline" , "Spare - incline" .)