Impossible job in remote settlement (7)
I believe the answer is:
outpost
'remote settlement' is the definition.
(I've seen this in another clue)
'impossible job' is the wordplay.
'impossible' becomes 'out' (out can mean no longer possible).
'job' becomes 'post' (post is a kind of job).
'out'+'post'='OUTPOST'
'in' acts as a link.
(Other definitions for outpost that I've seen before include "Remote part of an empire" , "Distant office, settlement" , "Outlying settlement" , "Remote military site" , "Remote military camp" .)