Last word of "America the Beautiful" (3)
I believe the answer is:
sea
'last word of america the beautiful' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sea that I've seen before include "The Med, e.g." , "eg Dead, Red" , "All at . . . - totally confused" , "Vast expanse" , "Cause of flooding" .)