Callas possibly missing intro in this? (4)

I believe the answer is:

aria

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'callas possibly missing intro in this?' is the definition.
The definition suggests a singular noun which matches the answer.

This is all the clue.

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(Other definitions for aria that I've seen before include "complex song" , "Song such as "Your Tiny Hand is Frozen"" , "Operatic air" , "Song from an opera (4)" , "Opera solo" .)

I've seen this clue in The Independent.

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