Maybe not wholly proper Hapsburg (7)
I believe the answer is:
perhaps
'maybe' is the definition.
(synonyms)
'not wholly proper hapsburg' is the wordplay.
'not wholly' says the answer is hidden in the clue (I've seen this in other clues).
'PERHAPS' is hidden within 'proper hapsburg'.
(Other definitions for perhaps that I've seen before include "Conceivably" , "say" , "Could be, maybe" , "Possibly but not certainly" , "Not necessarily" .)