Subduing, thanks to an old Chinese (6)
I believe the answer is:
taming
'subduing' is the definition.
('tame' can be a synonym of 'subdue')
'thanks to an old chinese' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'to an old chinese' becomes 'ming' (I can't explain this - if you can you should believe this answer much more).
'ta'+'ming'='TAMING'
Can you help me to learn more?
(Other definitions for taming that I've seen before include "Reducing an animal to a domestic state" , "Subjugation" , "Breaking" , "Overcoming wildness" , "The ...... of the Shrew (Shakespeare)" .)