Elementary particle London college discovered in gas (7)

I believe the answer is:

nucleon

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'elementary particle' is the definition.
(nucleon is a kind of elementary particle)

'london college discovered in gas' is the wordplay.
'london college' becomes 'ucl' (I can't justify this - if you can you should give a lot more credence to this answer).
'discovered in' indicates putting letters inside.
'gas' becomes 'neon' (neon is a gas).
'ucl' placed within 'neon' is 'NUCLEON'.

Can you help me to learn more?

(Other definitions for nucleon that I've seen before include "Particle" , "fundamental constituent" .)

I've seen this clue in The Times.

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