Common Words:
* abacus
* abrupt
* acquit
* adrift
* again
* aghast
* agile
* alight
* allied
* almost
* aroma
* around
* asleep
* attend
* august
* awaken
* award
Less Common Words:
* ablaze
* abroad
* adieu
* afresh
* agony
* aisle
* aloud
* altar
* amend
* angle
* aphid
* apron
* arbour
* ashen
* assign
* attune
* avowed
And some others:
* accuse
* across
* acted
* added
* adore
* adult
* advent
* afraid
* agreed
* aimed
* aired
* alert
* alike
* alive
* allow
* alone
* along
* altar
* amend
* angel
* angry
* apart
* appeal
* apply
* arise
* armed
* arrow
* asked
* atone
* avoid
* awake
* aware
* awful
This is not an exhaustive list, but it gives you a good starting point. You can use a dictionary or online word finder to discover even more six-letter words starting with "a".