Manorial cost unfortunately very large (12)
I believe the answer is:
astronomical
'very large' is the definition.
(I've seen this before)
'manorial cost unfortunately' is the wordplay.
'unfortunately' indicates anagramming the letters.
'manorial'+'cost'='manorialcost'
'manorialcost' anagrammed gives 'ASTRONOMICAL'.
(Other definitions for astronomical that I've seen before include "Absolutely huge, in a heavenly way" , "Really, really big" , "Tremendous" , "Massive" , "Enormous" .)