Spontaneous former English politician in split (9)
I believe the answer is:
extempore
'spontaneous' is the definition.
(thesaurus)
'former english politician in split' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'english' becomes 'E' (abbreviation).
'politician' becomes 'MP' (Member of Parliament).
'in' is an insertion indicator.
'split' becomes 'tore' (I've seen this in another clue).
'e'+'mp'='emp'
'emp' placed within 'tore' is 'tempore'.
'ex'+'tempore'='EXTEMPORE'
(Other definitions for extempore that I've seen before include "on spur of the moment" , "suddenly" , "Impromptu, improvised" , "Without preparation, of a speech say" , "Spoken or done without preparation, impromptu" .)