Constructed one large objection outside (5)
I believe the answer is:
built
'constructed' is the definition.
('build' can be a synonym of 'construct')
'one large objection outside' is the wordplay.
'one' becomes 'i' (Roman numeral).
'large' becomes 'L' (eg in clothes sizes).
'objection' becomes 'but' (as in 'no ifs, no buts').
'outside' is an insertion indicator (some letters go outside others).
'i'+'l'='il'
'il' placed into 'but' is 'BUILT'.
(Other definitions for built that I've seen before include "assembled" , "Raised" , "Erected" , "Made by combining materials and parts" , "Constructed" .)