Very happy experiencing levitation? (7,2,3)

I believe the answer is:

walking on air

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'levitation?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for walking on air that I've seen before include "In seventh heaven" , "Extremely happy" , "Highly elated" .)

I've seen this clue in The Times.

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