View expert immersed in paper (5)
I believe the answer is:
facet
'view' is the definition.
(I've seen this in other clues)
'expert immersed in paper' is the wordplay.
'expert' becomes 'ace' (ace is a kind of expert).
'immersed in' means one lot of letters goes inside another.
'paper' becomes 'ft'.
'ace' going within 'ft' is 'FACET'.
(Other definitions for facet that I've seen before include "Small surface (of diamond)" , "side of rock" , "Angle" , "Gem's cut side" , "view" .)