Tripe that fills active oven? (3,3)

I believe the answer is:

hot air

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'tripe' is the definition.
(thesaurus)

I don't understand the remainder of the clue.

(Other definitions for hot air that I've seen before include "Loud and empty talk to lift a balloon?" , "Bull" , "over the Sahara?" , "Bombast or balloon filler" , "Empty boastful talk; balloon lift provider" .)

I've seen this clue in The Telegraph.

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