A preposition seen in print only (4)
I believe the answer is:
into
'a preposition' is the definition.
(I've seen this in another clue)
'in print only' is the wordplay.
'in' says the answer is hidden in the clue.
'INTO' is hidden in the letters of 'print only'.
'seen' is the link.
(Other definitions for into that I've seen before include "Curious about" , "Liking" , "Knowledgeable about" , "ignition regularly missing" , "Not I (anag.)" .)