Politician apprehended by two African soldiers (4)
I believe the answer is:
impi
'african soldiers' is the definition.
(term for a group of Zulu warriors)
'politician apprehended by two' is the wordplay.
'politician' becomes 'MP' (Member of Parliament).
'apprehended by' is an insertion indicator (inserted letters are held or apprehended).
'two' becomes 'II' (Roman numerals).
'mp' going within 'ii' is 'IMPI'.
(Other definitions for impi that I've seen before include "Group of Bantu warriors" , "Armed band" , "African force" , "native warriors?" , "armed warriors" .)