Dance club certain about politician and old disturbance (12)
I believe the answer is:
discomposure
'old disturbance' is the definition.
'discomposure' can be an answer for 'disturbance' (thesaurus). I am unsure of the 'old' bit.
'dance club certain about politician' is the wordplay.
'dance club' becomes 'disco' (I've seen this before).
'certain' becomes 'sure' ('sure' can be a synonym of 'certain').
'about' means one lot of letters go next to another.
'politician' becomes 'mpo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sure' after 'mpo' is 'mposure'.
'disco'+'mposure'='DISCOMPOSURE'
'and' is the link.
(Other definitions for discomposure that I've seen before include "unease" , "Upset" .)