So energy invested in event
I believe the answer is:
really
'so energy invested in event' is the definition.
I can't tell whether this definition defines the answer.
'so energy invested in event' is the wordplay.
'so energy' becomes 'e' (physics symbol as in E=mc2. I am not sure about the 'so' bit.**).
'invested in' means one lot of letters goes inside another.
'event' becomes 'rally' (rally is a kind of event).
'e' going into 'rally' is 'REALLY'.
Can you help me to learn more?
(Other definitions for really that I've seen before include "Go on" , "Undoubtedly" , "Genuinely" , "Actually, no kidding" , "without a doubt" .)