Send insane, angered terribly (7)
I believe the answer is:
derange
'send insane' is the definition.
(a deranged person has gone insane)
'angered terribly' is the wordplay.
'terribly' indicates an anagram.
'angered' is an anagram of 'DERANGE'.
(Other definitions for derange that I've seen before include "Madden" , "Upset" , "Craze" , "Remove from order" , "Put into confusion" .)