Raphael's first avoids glazing detail, creating illusion (9,5)
I believe the answer is:
vanishing point
'illusion' is the definition.
(illusion of depth in a picture)
'raphael's first avoids glazing detail' is the wordplay.
'raphael's first' becomes 'r' (1st letter of 'raphael').
'avoids' indicates named letters should be taken away.
'glazing' becomes 'varnishing'.
'detail' becomes 'point' (synonyms).
'varnishing' with 'r' taken away is 'vanishing'.
'vanishing'+'point'='VANISHING POINT'
'creating' acts as a link.
(Other definitions for vanishing point that I've seen before include "One may see this in perspective" , "It helps one maintain a proper perspective" , "Where parallel lines meet in perspective" , "Result of bluntness" , "It helps create a sense of perspective" .)