Rational soldier in pub (7)
I believe the answer is:
logical
'rational' is the definition.
(similar in meaning)
'soldier in pub' is the wordplay.
'soldier' becomes 'GI' (GI can mean a US soldier).
'in' is an insertion indicator.
'pub' becomes 'local' (one's local pub).
'gi' placed inside 'local' is 'LOGICAL'.
(Other definitions for logical that I've seen before include "Consistent with reason" , "Well thought out" , "clear" , "According with reason" , "Clearly and soundly reasoned" .)