Couldn't stand to see - hated terribly (7)
I believe the answer is:
loathed
'couldn't stand' is the definition.
(I've seen this in another clue)
'see hated terribly' is the wordplay.
'see' becomes 'lo' (archaic exclamation meaning 'look!').
'terribly' indicates an anagram.
'hated' anagrammed gives 'athed'.
'lo'+'athed'='LOATHED'
'to' acts as a link.
(Other definitions for loathed that I've seen before include "'Abhorred, detested (7)'" , "Detested and abominated" , "Regarded with disgust and hatred" , "Hated" , "Cordially detested" .)