Published letters seen as settlement some way off (7)
I believe the answer is:
outpost
'settlement some way off' is the definition.
'published letters' is the wordplay.
'published' becomes 'out' (I've seen this in other clues).
'letters' becomes 'post' (I've seen this before).
'out'+'post'='OUTPOST'
'seen as' acts as a link.
(Other definitions for outpost that I've seen before include "Distant part (of empire)" , "isolated settlement" , "Remote settlement" , "Remote stronghold" , "Remote military site" .)