Turns on the waterworks (4)
I believe the answer is:
sobs
'turns on the waterworks' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sobs that I've seen before include "Weeps noisily" , "Given evidence of distress" , "Cries loudly" , "Cries noisily" , "Weeps audibly" .)