Not entirely bothered if I certify large building (7)
I believe the answer is:
edifice
'large building' is the definition.
(I've seen this before)
'not entirely bothered if i certify' is the wordplay.
'not entirely' says the answer is hidden in the clue.
'EDIFICE' is hidden within 'bothered if i certify'.
(Other definitions for edifice that I've seen before include "impressive pile!" , "Grand building" , "'Large, imposing building (7)'" , "Large structure" , "Construction" .)