Crossword Genius

Daughter engaged in excuse, mostly dreamt up on the spot (2-3)

Ross

I believe the answer is:

ad-lib

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(Other definitions for ad-lib that I've seen before include "Depart from the text" , "Speak off the cuff" , "Talk without notes" , "Speak without preparation" , "Unprepared remark" .)

I've seen this clue in The Times.
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