China's most populous city (8)
I believe the answer is:
shanghai
'china's most populous city' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for shanghai that I've seen before include "once used to drug sailors, possibly" , "Trick someone into joining a ship's crew unwillingly (in China?)" , "Largest city in China" , "How to impress a sailor" , "[YANGTZE] 's mouth here?" .)