If you break sugar press, he will tell on you (10)
I believe the answer is:
supergrass
'you' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'if you break sugar press he will tell' is the wordplay.
'sugar press' can be anagrammed to 'SUPERGRASS'.
But, I'm unsure how the anagram is indicated.
'on' is the link.
Can you help me to learn more?
(Other definitions for supergrass that I've seen before include "He does a lot of shopping" , "Very important police informer" , "Repentant criminal perhaps" , "Large-scale informer" .)