Expert appearing in newspaper feature (5)
I believe the answer is:
facet
'feature' is the definition.
(facet is a kind of feature)
'expert appearing in newspaper' is the wordplay.
'expert' becomes 'ace' (ace is a kind of expert).
'appearing in' means one lot of letters goes inside another.
'newspaper' becomes 'ft'.
'ace' put into 'ft' is 'FACET'.
(Other definitions for facet that I've seen before include "Small flat surface of cut gemstone" , "Particular aspect" , "Aspect or feature of something" , "side of rock" , "Angle" .)