Peer at actor, desperately holding teacher back (10)
I believe the answer is:
aristocrat
'peer' is the definition.
(thesaurus)
'at actor desperately holding teacher back' is the wordplay.
'desperately' indicates anagramming the letters.
'holding' is an insertion indicator.
'teacher' becomes 'sir' (way of addressing a male teacher).
'back' says the letters should be written backwards.
'sir' written backwards gives 'ris'.
'actor' is an anagram of 'ocrat'.
'at'+'ocrat'='atocrat'
'atocrat' enclosing 'ris' is 'ARISTOCRAT'.
(Other definitions for aristocrat that I've seen before include "Nobleman" , "Patrician" , "toff" , "Nob" , "Noble" .)