Colluding with China, so has to react (2,7)
I believe the answer is:
in cahoots
'colluding' is the definition.
(I've seen this in another clue)
'china so has to react' is the wordplay.
'has' is a charade indicator (letters next to each other).
'react' indicates anagramming the letters (I've seen 'reacting' mean this).
'china'+'so'+'to'='chinasoto'
'chinasoto' anagrammed gives 'IN CAHOOTS'.
'with' acts as a link.
(Other definitions for in cahoots that I've seen before include "what conspirators are" , "Thick" , "Associated with" , "Conspiring together" , "Colluding" .)