This mostly is associated with US city club (5)
I believe the answer is:
lathi
'club' is the definition.
(type of baton used in British India)
'this mostly is associated with us city' is the wordplay.
'mostly' means to remove the last letter.
'is associated with' is a charade indicator (letters next to each other).
'us city' becomes 'LA' (short for Los Angeles).
'this' with its final letter taken off is 'thi'.
'thi' put after 'la' is 'LATHI'.
(Other definitions for lathi that I've seen before include "club in India" , "Weapon police may use" , "Indian police baton" , "Long, heavy stick" , "Indian truncheon" .)