Person sent up: I hate that -- stop it! (6)
I believe the answer is:
enough
'stop it' is the definition.
(both can be used to tell someone to stop something)
'person sent up i hate that' is the wordplay.
'person' becomes 'one' ('one' can mean an unspecified person).
'sent up' says the letters should be written in reverse.
'i hate that' becomes 'ugh' (exclamation of disgust).
'one' written backwards gives 'eno'.
'eno'+'ugh'='ENOUGH'
(Other definitions for enough that I've seen before include "As much as desired" , "As many as are required" , "As much as desirable" , "Sufficient to answer demand" , "Adequate, sufficient" .)