River traversed by solitary person who lives near the Thames? (8)
I believe the answer is:
londoner
'who lives near the thames?' is the definition.
'river traversed by solitary person' is the wordplay.
'river' becomes 'don' (I've seen this before).
'traversed by' is an insertion indicator.
'solitary person' becomes 'loner' (I've seen this before).
'don' put inside 'loner' is 'LONDONER'.
(Other definitions for londoner that I've seen before include "capitalist?" , "city dweller" , "Inhabitant of capital" , "Possible Cockney" , "Resident of the UK capital" .)