Bird -- large one found in typical American pie (7)
I believe the answer is:
pelican
'bird' is the definition.
(pelican is a kind of bird)
'large one found in typical american pie' is the wordplay.
'large' becomes 'l'.
'one' becomes 'i' (Roman numeral).
'found in' indicates putting letters inside.
'typical american pie' becomes 'pecan' (pecan pie is a typical US dish).
'l'+'i'='li'
'li' placed inside 'pecan' is 'PELICAN'.
(Other definitions for pelican that I've seen before include "Large aquatic bird" , "Large bird with pouch in bill for storing fish" , "Large water bird" , "One presenting big bill" , "Seabird having a large bill with a pouch for fish" .)