Reading through "America At Large" (7)
I believe the answer is:
perusal
'reading' is the definition.
(I know that perusal is a type of reading)
'through america at large' is the wordplay.
'through' becomes 'per' ('per' can mean through or by means of).
'america' becomes 'usa' (United States of America).
'at' means one lot of letters go next to another.
'large' becomes 'L' (eg in clothes sizes).
'per'+'usa'+'l'='PERUSAL'
(Other definitions for perusal that I've seen before include "worth a close look" , "Careful reading" , "Thorough read-through" , "Examination, survey" , "Inspection" .)