Certainly endless energy directed upward turned the air blue (5)

I believe the answer is:

effed

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'turned the air blue' is the definition.
The definition and answer can be both to do with contact as well as being past participle verbs.
Perhaps there's a link between them I don't understand?

'certainly endless energy directed upward' is the wordplay.
'certainly' becomes 'deffo' (short for definitely).
'endless' says to take the centre.
'energy' becomes 'e' (physics symbol as in E=mc2).
'directed upward' becomes 'd' (I am not sure about this - if you are sure you should believe this answer much more).
The central letters of 'deffo' are 'eff'.
'eff'+'e'+'d'='EFFED'

Can you help me to learn more?

I've seen this clue in The Guardian.

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