Clue: That is upsetting about BBC boss — untouchable but showing nerves (8)
Answer: EDGINESS
Explanation: Definition: nerves
IE=i.e.="That is" reversed/"upsetting", and around DG (Director General, "BBC boss"), then plus NESS="untouchable" 
Eliot NESS was one of the 'Untouchables", US law enforcement agents during Prohibition