Atatime

11 clues
One ___
Together
Concurrently
One thing ___
Simultaneously
One ___ (singly)
End of the quotation
Completion of "one day
One Day ___," TV sitcom
Unit by unit in succession
Orderly phrase that can follow one, two or three
Similar answers:
Abatable
Abcdaytimehosts
Abedtimestory
Abouttime
Abouttimetoo
Acatmaylookataking
Actiontime
Adventuretime
Afewtimes
Afrikabambaataa
Afteratime
Agoodtimetokeep
Agreatadvantage
Ahardtime
Aheadofonestime
Aheadoftime
Aiatas
Aintthatabitch
Aintthatasham
Aintthatashame