Attacks when one throws the switch (5,2)
I believe the answer is:
turns on
'throws the switch' is the definition.
'turns on' can be an answer for 'throws' (turning on is a kind of throwing). I'm not sure about the 'the switch' bit.
'attacks when one' is the wordplay.
I cannot quite understand how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is found within the answer.
The remaining letters 'turns' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for turns on that I've seen is " Lays into".)