In China I'm stopping trains (4)
I believe the answer is:
aims
'trains' is the definition.
('aim' can be a synonym of 'train')
'in china i'm stopping' is the wordplay.
'in' indicates a hidden word.
'AIMS' is hidden within 'china im stopping'.
(Other definitions for aims that I've seen before include "Sets sight on, having ambitions" , "Trains - intentions" , "Objectives; points" , "Purposes or intentions" , "Objectives, purposes" .)