Member of a governing body (7)
I believe the answer is:
senator
'member of a governing body' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for senator that I've seen before include "Member of upper house of legislature" , "Member of upper house commits treason?" , "Treason by member of parliament" , "Member of Upper House engaged in treason" , "Upper house US Congressman" .)