Unacceptable, but past help, ate out (6,3,4)
I believe the answer is:
beyond the pale
'unacceptable' is the definition.
(I've seen this before)
'past help ate out' is the wordplay.
'past' becomes 'beyond' (I've seen this before**).
'out' indicates an anagram (out can mean wrong or inaccurate).
'help'+'ate'='helpate'
'helpate' anagrammed gives 'thepale'.
'beyond'+'thepale'='BEYOND THE PALE'
'but' is the link.
(Other definitions for beyond the pale that I've seen before include "Unacceptable (behaviour)" , "Outside the bounds of acceptable behaviour" , "Not understood by untanned people" , "Intolerable, unacceptable" , "Socially unacceptable" .)