Traitor in Paris who has basic weapon (8)
I believe the answer is:
quisling
'traitor' is the definition.
(quisling is a kind of traitor)
'paris who has basic weapon' is the wordplay.
'paris who' becomes 'qui'.
'has' is a charade indicator (letters next to each other).
'basic weapon' becomes 'sling'.
'qui'+'sling'='QUISLING'
'in' is the link.
(Other definitions for quisling that I've seen before include "Wartime collaborator" , "(Norwegian) WWII collaborator" , "Traitorous collaborator" , "Collaborator with an occupying force" , "Traitor who aids an occupying enemy force" .)