Expected level (4)
'expected level' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for par that I've seen before include "Average standard" , "Rating of strokes required for hole (golf)" , "Average or even, as for the course" , "Normal golfing score" , "Average score for round of golf" .)
(Other definitions for norm that I've seen before include "Rule; average" , "expected thing" , "'Standard, usual (4)'" , "(The) accepted way" , "Typical, usual" .)