Book describing a conservation area (7)

I believe the answer is:

reserve

I believe this clue is a double definition.

'book' is the first definition.
(as in booking or reserving in advance)

'a conservation area' is the second definition.
(I've seen this before)

'describing' acts as a link.

(Other definitions for reserve that I've seen before include "Set aside - shyness" , "8 [RESTRAINT]" , "Lack of openness" , "Husband - substitute" , "cool" .)

I've seen this clue in The Globe and Mail.

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