THEME: ITEM found in phrases
GOOD ONES: With {AGENDA} and {theme} HIDDEN [thus ITEM which is HIDDEN in the phrases is part of the AGENDA]
Start to push? PEE
Flat container SHOEBOX [flats are shoes, or they were]
Where age goes before beauty, briefly OED [alphabetically, that is, in the Oxford]
BTW: "Absolutely!" YESICAN [if this is a worthy clue, then virtually any word or phase would do: "of course"; "you can't"; "likely" …]
ATOI is never used in our language, but "A to I" might be.
RATING:
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun