Not quite sober, show dissent (5)
I believe the answer is:
demur
'dissent' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for demur that I've seen before include "Protest or disagree mildly" , "Waver" , "Protest mildly, show reluctance" , "Hesitation" , "Raise scruples" .)