Did out, and sexed up, Post Office interior (7)
I believe the answer is:
exposed
'did out' is the definition.
(do out can mean to expose)
'sexed up post office interior' is the wordplay.
'up' indicates an anagram (letters get chucked up).
'post office' becomes 'po' (abbreviation).
'interior' means one lot of letters goes inside another.
'sexed' anagrammed gives 'exsed'.
'exsed' placed around 'po' is 'EXPOSED'.
'and' is the link.
(Other definitions for exposed that I've seen before include "Like a dummy" , "Unmasked, revealed" , "Made public" , "Deprived of cover" , "Made known" .)