Unbroken channel round outskirts of Greenwich (8)
I believe the answer is:
straight
'unbroken' is the definition.
(thesaurus)
'channel round outskirts of greenwich' is the wordplay.
'channel' becomes 'strait' (strait is a kind of channel**).
'round' is an insertion indicator.
'outskirts of' means to remove the middle letters.
'greenwich' with its centre removed is 'gh'.
'strait' enclosing 'gh' is 'STRAIGHT'.
(Other definitions for straight that I've seen before include "Serious" , "Undeviating" , "Respectable" , "Neat (of drinks)" , "Frank" .)