One that’s inclined to see endless pain in face (8)
I believe the answer is:
diagonal
'one that's inclined to' is the definition.
I can't tell whether this defines the answer.
'endless pain in face' is the wordplay.
'endless pain' becomes 'agon' (I've seen this in other clues).
'in' means one lot of letters goes inside another.
'face' becomes 'dial' (face of a clock).
'agon' put into 'dial' is 'DIAGONAL'.
'see' is the link.
Can you help me to learn more?
(Other definitions for diagonal that I've seen before include "Sloping line" , "bishop controls it" , "bishop moves here" , "Corner-to-corner line" , "straight line from corner" .)