Do this to let Chinese speak on taboo subject (5,3,7)

'do this to let chinese speak' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'on taboo subject' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is located in the answer.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?