It is, dear one, a flower (7)

I believe the answer is:

petunia

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'flower' is the definition.
(type of flower)

'it is dear one a' is the wordplay.
'it is dear' becomes 'pet' (I've seen this in other clues).
'one' becomes 'uni' (I can't explain this - if you can you should give a lot more credence to this answer).
'pet'+'uni'+'a'='PETUNIA'

Can you help me to learn more?

(Other definitions for petunia that I've seen before include "Plant related to tobacco" , "Garden plant with large funnel-shaped flower" , "Colourful" , "Common garden plant" , "Flower much used in hanging baskets" .)

I've seen this clue in the Evening Standard.

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