Parsec

3 clues
Astronomical unit
Astronomical distance
Astronomical unit of distance
Similar answers:
1sec
Aballparkfigure
Abenchinthepark
Abovepar
Aboveparade
Abrightparticularstar
Abruptdeparture
Achirpinginsect
Acompartment
Actapart
Actofparliament
Actsapart
Actsthepart
Actthepart
Adepartmentstoreandhe
Afterafterparty
Afterparty
Aidoftheirparty
Airapparent
Airborneparasolsites