Bed one rises to go to (4,6)

I believe the answer is:

roof garden

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'bed' is the definition.
(thesaurus)

I don't understand the remainder of the clue.

(Other definitions for roof garden that I've seen before include "where domestic growth high?" , "High-level greenery" , "Elevated area of greenery" , "that's grown at highest level" , "where domestic growth is highest" .)

I've seen this clue in The Telegraph.

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