Chinese gelatin (4)
I believe the answer is:
agar
'chinese gelatin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for agar that I've seen before include "Food thickening agent obtained from seaweed" , "Jelly medium" , "contribution to culture?" , "Seaweed jelly" , "Medium for growth" .)