Ultimately upstanding, awfully strange criminal (8)
I believe the answer is:
gangster
'criminal' is the definition.
(I know that gangster is a type of criminal)
'ultimately upstanding awfully strange' is the wordplay.
'ultimately' indicates one should take the final letters.
'awfully' is an anagram indicator.
The final letter of 'upstanding' is 'g'.
'strange' is an anagram of 'angster'.
'g'+'angster'='GANGSTER'
(Other definitions for gangster that I've seen before include "Mafia man" , "Member of a mob like Al Capone" , "Member of criminal group" , "Typical Cagney role" , "Soprano possibly" .)