Decaying muon lit up some dangerous stuff (9)
I believe the answer is:
plutonium
'dangerous stuff' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'decaying muon lit up' is the wordplay.
'decaying' indicates anagramming the letters (the original order breaks down).
'muon'+'lit'+'up'='muonlitup'
'muonlitup' anagrammed gives 'PLUTONIUM'.
'some' acts as a link.
Can you help me to learn more?
(Other definitions for plutonium that I've seen before include "sign of this bomb-making material" , "Nuclear material" , "Fuel for nuclear reactors" , "Radioactive element" , "Radioactive material, Pu" .)