What MP has turned up about good man's proclivities (6)
I believe the answer is:
tastes
'proclivities' is the definition.
'what mp has turned up about good man's' is the wordplay.
'what mp has' becomes 'seat' (MPs have seats in the House of Commons).
'turned up' is a reversal indicator.
'about' indicates putting letters inside.
'good man's' becomes 'st' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'seat' reversed gives 'taes'.
'taes' enclosing 'st' is 'TASTES'.
(Other definitions for tastes that I've seen before include "Savourings or penchants" , "Samples the flavour of" , "Experiences" , "Likings as for food sensations" , "Flavours or penchants" .)