Dissident ordered beer, litres (5)
I believe the answer is:
rebel
'dissident' is the definition.
(rebel is a kind of dissident)
'ordered beer litres' is the wordplay.
'ordered' indicates an anagram.
'litres' becomes 'l'.
'beer' with letters rearranged gives 'rebe'.
'rebe'+'l'='REBEL'
(Other definitions for rebel that I've seen before include "He resists authority" , "Rise up - dissent" , "Disobey" , "Rise in armed opposition" , "Flouter of authority" .)