V at n
With three verbs, the prepositional phrase is an Adjunct. Only one noun, or a very restricted range of nouns, can occur in the prepositional phrase.
fray (at the edges/collar/cuffs) froth (at the mouth) wait (at table)
He was wearing a grey cotton jacket and a shirt which was fraying at the collar.
Marie would cook a meal for them and Jean would wait at table.