Reminisce about MP (8)
I believe the answer is:
remember
'reminisce' is the definition.
(to reminisce is to think about the past)
'about mp' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'mp' becomes 'member' (Member of Parliament).
're'+'member'='REMEMBER'
(Other definitions for remember that I've seen before include "Recall to mind" , "Commemorate" , "Retain memory of" , "Call to mind" , "Mark" .)