Really great grass! (6)

I believe the answer is:

bamboo

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

'grass' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for bamboo that I've seen before include "Treelike tropical grass" , "Tropical cane with hollow centres, used for furniture" , "Spotted tile; carnival mask" , "Tall woody plant" , "Tall wood plant" .)

I've seen this clue in the Evening Standard.

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