Inclination to fade away, in general (8)
I believe the answer is:
gradient
'inclination' is the definition.
(gradient is a kind of inclination)
'fade away in general' is the wordplay.
'fade away' becomes 'die' (I've seen this in other clues).
'in' means one lot of letters goes inside another.
'general' becomes 'grant' (Grant is an example).
'die' put inside 'grant' is 'GRADIENT'.
'to' acts as a link.
(Other definitions for gradient that I've seen before include "Measure of slope" , "Rise" , "Treading (anag) - slope" , "Perhaps one in ten" , "Angle of slope" .)