Some seven letter words with the second letter A and the third letter U are:
7 letter word 3rd letter x
agelessagonizeegotistignitesigneous
possess
Animals
economy
shifted
transom
Requiem?
Amassed
garbage
cabinetcaboosedebtorsrebuiltonboardmobsterreboundsubsidywebsitetabletssubwayslobsterreboundrebateslibraryrabbitsdebrieffibbingembraceembargolabeledorbitedrebirth
Behoove.
ardvark
7 letter word 3rd letter x
7 letter word 3rd letter x
Oedipal
agelessagonizeegotistignitesigneous