Funny thing that is worn to bed (7)

I believe the answer is:

nightie

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'worn to bed' is the definition.
I can't tell whether this definition defines the answer.

'funny thing that is' is the wordplay.
'funny' indicates an anagram.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'thing' anagrammed gives 'night'.
'night'+'ie'='NIGHTIE'

Can you help me to learn more?

(Other definitions for nightie that I've seen before include "Late shift perhaps" , "Familiar bed-wear for woman" , "Clothing worn in bed" , "one put on after dark" , "Skimpy attire" .)

I've seen this clue in the Sydney Morning Herald.

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