Magnum takes this local train? (7)
I believe the answer is:
stopper
I believe this is a double definition.
'magnum takes this' is the first definition.
(as in a bottle stopper - magnum is a bottle size)
'local train?' is the second definition.
(stopping train)
(Other definitions for stopper that I've seen before include "One blocks" , "Plug for a bottle" , "Bung" , "Perhaps cork" , "Maybe cork" .)