Dialect used by papers on the Isle of Man (5)
I believe the answer is:
idiom
'dialect' is the definition.
(I know that dialect can be written as idiom)
'papers on the isle of man' is the wordplay.
'papers' becomes 'ID' (identification papers).
'on' is a charade indicator (letters next to each other).
'the isle of man' becomes 'iom'.
'id'+'iom'='IDIOM'
'used by' acts as a link.
(Other definitions for idiom that I've seen before include "Special linguistic usage" , "'Break a leg' or 'miss the boat'" , "Group of words in which the meaning may not be obvious" , "Vocabulary characteristic of a specific group" , "Colloquial saying" .)