Fake member of parliament initially says Latin must be included (3,3)
I believe the answer is:
peg leg
'fake member' is the definition.
(member can mean a limb)
I don't understand the rest of the clue.
(Other definitions for peg leg that I've seen before include "Person with a wooden limb" , "Artificial limb (informal)" , "Silver piece's replacement" , "Informally, an artificial lower limb" , "Eg. Long John Silver" .)