Man behaving dishonourably — Conservative, notice (3)
I believe the answer is:
cad
'man' is the definition.
(I have seen 'Dishonourable man ' mean 'cad' so perhaps 'man' could also mean 'cad')
'conservative notice' is the wordplay.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'notice' becomes 'ad'.
'c'+'ad'='CAD'
'behaving dishonourably' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cad that I've seen before include "One behaves dishonourably" , "Rogue" , "Stinker" , "he's no gent" , "Dishonourable man of decadent sort" .)