Unfamiliar run for paper (9)
I believe the answer is:
newsprint
'for paper' is the definition.
(newsprint is a kind of paper)
'unfamiliar run' is the wordplay.
'unfamiliar' becomes 'new' (I've seen this in other clues).
'run' becomes 'sprint' (sprinting is a kind of running).
'new'+'sprint'='NEWSPRINT'
(Other definitions for newsprint that I've seen before include "FT for example" , "needed for the papers" , "Kind of paper this is produced on" , "Bearer of tidings" , "Low-quality paper" .)