Transported con's last in jail but being reformed (8)
I believe the answer is:
jubilant
'transported' is the definition.
(thesaurus)
'con's last in jail but being reformed' is the wordplay.
'last' indicates one should take the final letters.
'in' means one lot of letters goes inside another.
'being reformed' indicates anagramming the letters.
The last letter of 'con' is 'n'.
'jail'+'but'='jailbut'
'jailbut' with letters rearranged gives 'jubilat'.
'n' put inside 'jubilat' is 'JUBILANT'.
(Other definitions for jubilant that I've seen before include "Cock-a-hoop" , "Shouting with joy" , "In transport" , "Showing extreme joy" , "Happy, triumphant" .)