Controversial treatment of hair, with article (hammer?) hitting your head! (5,7)

'controversial treatment' is the definition.
(electroconvulsive therapy)

'hair with article hammer? hitting your head' is the wordplay.
I cannot quite see how this works, but
'hair' could be 'shock' (I've seen this before) and 'shock' is found within the answer.
'article' could be 'the' (the definite article in English) and 'the' is present in the answer.
'hammer?' could be 'rap' (both can mean to hit) and 'rap' is found in the answer.
A single letter 'y' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'of' is the link.

Can you help me to learn more?