Advance point of view in matter (9)
I believe the answer is:
substance
'matter' is the definition.
('substance' can be a synonym of 'matter')
'advance point of view' is the wordplay.
'advance' becomes 'sub' (I've seen this in other clues).
'point of view' becomes 'stance' (I've seen this before).
'sub'+'stance'='SUBSTANCE'
'in' acts as a link.
(Other definitions for substance that I've seen before include "Basic matter" , "Subject matter" , "Matter or material that a thing is made of" , "wealth" , "Physical matter" .)