Part of leg the person speaking in a part raised (5)
I believe the answer is:
tibia
'part of leg' is the definition.
('tibia' is part of 'leg')
'the person speaking in a part raised' is the wordplay.
'the person speaking' becomes 'i' ('I' refers to the person who says it).
'in' is an insertion indicator.
'part' becomes 'bit' (both mean a piece of something).
'raised' says the letters should be written in reverse.
'a'+'bit'='abit'
'i' placed inside 'abit' is 'aibit'.
'aibit' backwards is 'TIBIA'.
(Other definitions for tibia that I've seen before include "Bone in osso bucco" , "part of skeleton" , "Part of leg of" , "Shin bone" , "ancient pipe" .)