House number kept under wraps by owner (7)

I believe the answer is:

hanover

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

I can't explain the rest of the clue.

(Other definitions for hanover that I've seen before include "German 22 Across" , "10 [HOUSE]" , "Royal house from George I to Victoria" , "Royal house after Stuarts" , "German town, and royal house" .)

I've seen this clue in The Telegraph.

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