It's reasonable for a soldier to go in a pub (7)
I believe the answer is:
logical
'it's reasonable' is the definition.
('logical' can be similar in meaning to 'reasonable')
'a soldier to go in a pub' is the wordplay.
'a soldier' becomes 'gi' (government issue or general issue).
'to go in' means one lot of letters goes inside another.
'a pub' becomes 'local' (I've seen this before).
'gi' inserted within 'local' is 'LOGICAL'.
'for' acts as a link.
(Other definitions for logical that I've seen before include "Based on reason" , "Consistent with reason" , "Deducible" , "Showing rational thought" , "Well thought out" .)