In Piccadilly, a tasteful addition (4)

I believe the answer is:

dill

I'm a little stuck... Click here to teach me more about this clue!

'tasteful addition' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.

'in piccadilly a' is the wordplay.
'in' indicates a hidden word.
'DILL' is hidden in the letters of 'piccadilly a'.

Can you help me to learn more?

(Other definitions for dill that I've seen before include "Herb; rhymes with beak" , "Fool" , "Culinary herb" , "medicinal plant" , "Herb with thread-like foliage used as seasoning" .)

I've seen this clue in the Evening Standard.

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