Perhaps this phrase means something different in British English, but in American English "out of the cellar" simply means to take out or release or remove from the cellar (which is like a basement, or storage area underneath a house).
"I brought the rest of the beer up out of the cellar for the party." (I carried the beer upstairs out of the basement.)
"Mom was on her way home, so I let my brother out of the cellar." (Implies that my brother was being a nuisance, so I locked him in the basement.)
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