US soldier in pub reasoned correctly (7)
I believe the answer is:
logical
'reasoned correctly' is the definition.
(logical means reasoned or rational)
'us soldier in pub' is the wordplay.
'us soldier' becomes 'GI' (informal term for a US soldier).
'in' indicates putting letters inside.
'pub' becomes 'local' (one's local pub).
'gi' going inside 'local' is 'LOGICAL'.
(Other definitions for logical that I've seen before include "Following correct reasoning" , "In accordance with reason" , "Sound" , "Well-reasoned" , "Deductive" .)