Involve republican in mobile assembly (7)
I believe the answer is:
embroil
'involve' is the definition.
(I know that embroil is a more specific form of involve)
'republican in mobile assembly' is the wordplay.
'republican' becomes 'R' (political abbreviation).
'in' is an insertion indicator.
'assembly' indicates anagramming the letters.
'mobile' with letters rearranged gives 'emboil'.
'r' put into 'emboil' is 'EMBROIL'.
(Other definitions for embroil that I've seen before include "Deeply involve (someone in something)" , "Drag in - bole rim (anag)" , "get into trouble" , "Bring into confusion" , "Implicate" .)