Religious school hit new peak (6)
I believe the answer is:
zenith
'peak' is the definition.
(I've seen this before)
'religious school hit new' is the wordplay.
'religious school' becomes 'zen' (school of Buddhism).
'new' indicates an anagram.
'hit' is an anagram of 'ith'.
'zen'+'ith'='ZENITH'
(Other definitions for zenith that I've seen before include "Point directly above the nadir" , "Top point" , "Highest point (on celestial sphere)" , "Point in sky directly overhead" , "The highest point overhead" .)