Building Ann leaves in defiance perhaps (7)
I believe the answer is:
edifice
'building' is the definition.
(I know that building can be written as edifice)
'ann leaves in defiance perhaps' is the wordplay.
'leaves' is a deletion indicator.
'perhaps' is an anagram indicator.
'in'+'defiance'='indefiance'
'indefiance' with 'ann' taken out is 'idefice'.
'idefice' anagrammed gives 'EDIFICE'.
(Other definitions for edifice that I've seen before include "'Large, imposing building (7)'" , "impressive pile!" , "Permanent building" , "erection" , "Construction" .)