Also, do take Leo in to say goodbye (6-2)

I believe the answer is:

toodle-oo

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'in to say goodbye' is the definition.
I can't tell whether this definition defines the answer.

'also do take leo' is the wordplay.
'also' becomes 'too' (synonyms).
'take' means one lot of letters goes inside another.
'do' placed around 'leo' is 'dleoo'.
'too'+'dleoo'='TOODLE-OO'

Can you help me to learn more?

(Other definitions for toodle-oo that I've seen before include "Ta-ta" , "Goodbye (dated)" , "Cheerio" , "Farewell (old inf.)" , "Bye-bye!" .)

I've seen this clue in the Evening Standard.

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