Small demonstration on nuclear front shows spirit (5)

I believe the answer is:

demon

I'm a little stuck... Click here to teach me more about this clue!

'spirit' is the definition.
(I know that demon is a type of evil spirit)

'small demonstration on nuclear front' is the wordplay.
'small demonstration' becomes 'demo' (synonyms. I am not sure about the 'small' bit.).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'front' suggests taking the first letters.
The first letter of 'nuclear' is 'n'.
'demo'+'n'='DEMON'

'shows' is the link.

Can you help me to learn more?

(Other definitions for demon that I've seen before include "Skilful person" , "Familiar" , "Fiend, devil" , "Wizard" , "Evil spirit or cruel person" .)

I've seen this clue in the Sydney Morning Herald.

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