Last, final (8)
I believe the answer is:
ultimate
I believe this clue is a double definition.
'last' is the first definition.
(similar in meaning)
'final' is the second definition.
(similar in meaning)
(Other definitions for ultimate that I've seen before include "Utmost or extreme" , "Conclusive" , "Final - mutilate (anag)" , "Mutilate in final way" , "Utmost; last" .)