Old politician supporting current Conservative bugs partner (10)
I believe the answer is:
accomplice
'partner' is the definition.
(I've seen this before)
'old politician supporting current conservative bugs' is the wordplay.
'old politician' becomes 'co' (I can't justify this - if you can you should give a lot more credence to this answer).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'current' becomes 'ac' (alternating current).
'conservative' becomes 'MP' (Member of Parliament).
'bugs' becomes 'lice' (plural of louse).
'co' after 'ac' is 'acco'.
'acco'+'mp'+'lice'='ACCOMPLICE'
Can you help me to learn more?
(Other definitions for accomplice that I've seen before include "Partner in plan" , "Partner in crime" , "criminal partner" , "ally" , "Fellow criminal" .)