Apparition produced by artist with pens (6)
I believe the answer is:
wraith
'apparition' is the definition.
(wraith is a kind of apparition)
'artist with pens' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'pens' means one lot of letters goes inside another (to pen can mean to contain or imprison).
'ra' inserted inside 'with' is 'WRAITH'.
'produced by' acts as a link.
(Other definitions for wraith that I've seen before include "Ghost, spectral apparition" , "Presence" , "Making an emotional appeal" , "Ghost-like apparition" , "Spook" .)