It grows in Berlin, densely (6)

I believe the answer is:

linden

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'it grows' is the definition.
The definition suggests a singular noun which matches the answer.

'in berlin densely' is the wordplay.
'in' indicates a hidden word.
'LINDEN' is hidden within 'berlin densely'.

Can you help me to learn more?

(Other definitions for linden that I've seen before include "type of tree" , "Tree with Lea - also called 8" , "Lime tree" , "One twigged" , "Unter den ------, iconic boulevard in Berlin" .)

I've seen this clue in the Evening Standard.

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