Like piano used for Killer Queen ? Quite the opposite, allegedly (3)

I believe the answer is:

asp

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'for killer queen ? quite the opposite allegedly' is the definition.
I can't tell whether this defines the answer.

'like piano' is the wordplay.
'like' becomes 'as'.
'piano' becomes 'p'.
'as'+'p'='ASP'

'used' is the link.

Can you help me to learn more?

(Other definitions for asp that I've seen before include "Small poisonous snake" , "Cleopatra's supposed nemesis" , "Pa's Cleopatra's killer" , "Cleopatra's poisoner" , "snake appears" .)

I've seen this clue in The Independent.

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