Ale, but so incredibly perfect (8)
I believe the answer is:
absolute
'perfect' is the definition.
(synonyms)
'ale but so incredibly' is the wordplay.
'incredibly' indicates anagramming the letters.
'ale'+'but'+'so'='alebutso'
'alebutso' with letters rearranged gives 'ABSOLUTE'.
(Other definitions for absolute that I've seen before include "Sheer, total, not limited" , "Complete - unlimited" , "Total, utter" , "Such a ruler is free from all limits" , "Literary captain" .)