Called into action: driven over the edge (8)
I believe the answer is:
deranged
'driven over the edge' is the definition.
I can't tell whether this definition defines the answer.
'called into action' is the wordplay.
'called' becomes 'rang' (called on the phone).
'into' indicates putting letters inside.
'action' becomes 'deed' (deed is a kind of action).
'rang' placed inside 'deed' is 'DERANGED'.
Can you help me to learn more?
(Other definitions for deranged that I've seen before include "What Ophelia was eventually" , "Upset" , "Made insane" , "bananas" , "Crackpot" .)