As tune changes, remove an MP, perhaps (6)
I believe the answer is:
unseat
'remove an mp perhaps' is the definition.
(remove from a parliamentary seat)
'as tune changes' is the wordplay.
'changes' indicates anagramming the letters.
'as'+'tune'='astune'
'astune' is an anagram of 'UNSEAT'.
(Other definitions for unseat that I've seen before include "Remove from power" , "Dislodge from saddle" , "Cause to fall from the saddle" , "Throw (as a 15?)" , "Get out of office" .)