Bit of a legend armed by French copper (8)
I believe the answer is:
gendarme
'french copper' is the definition.
(I've seen this in another clue)
'bit of a legend armed by' is the wordplay.
'bit of' indicates the answer is hidden within the clue.
'GENDARME' can be found hidden inside 'legend armed by'.
(Other definitions for gendarme that I've seen before include "Nice policeman" , "Member of the French police" , "continental copper" , "policeman in Paris?" , "Soldier on police duty" .)