Used in fission: new uranium crystal? (7)

I believe the answer is:

nuclear

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'used in fission' is the definition.
'nuclear' can be an answer for 'fission' (synonyms). I'm not certain of the 'used in' bit.

'new uranium crystal?' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'uranium' becomes 'U' (U is the chemical symbol for uranium).
'crystal?' becomes 'clear' (I am not sure about this - if you are sure you should believe this answer much more).
'n'+'u'+'clear'='NUCLEAR'

Can you help me to learn more?

(Other definitions for nuclear that I've seen before include "Clue ran oddly to atomic" , "Concerning subatomic particles" , "Relating to part of atom" , "Using atomic energy" , "Such a bomb" .)

I've seen this clue in The Sun.

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