Fantastic, bizarre claim about silver (7)

I believe the answer is:

magical

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'fantastic' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?

'bizarre claim about silver' is the wordplay.
'bizarre' is an anagram indicator.
'about' indicates putting letters inside.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'claim' with letters rearranged gives 'mical'.
'mical' going around 'ag' is 'MAGICAL'.

Can you help me to learn more?

(Other definitions for magical that I've seen before include "Enchanting or spell-binding" , "Fascinating - occult" , "Occult, supernatural" , "Enchanted" , "charmed" .)

I've seen this clue in The Daily Express.

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