Concerning speck far away (6)
I believe the answer is:
remote
'far away' is the definition.
(I've seen this before)
'concerning speck' is the wordplay.
'concerning' becomes 're'.
'speck' becomes 'mote' ('mote' can be a synonym of 'speck').
're'+'mote'='REMOTE'
(Other definitions for remote that I've seen before include "Distant like meteor (6)" , "Slight possibility" , "Far-flung" , "Controller of programmes" , "Far off; outside (chance)" .)