New exam must include end of term average (6)
I believe the answer is:
normal
'average' is the definition.
(similar in meaning)
'new exam must include end of term' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'exam' becomes 'oral' (spoken academic test).
'must include' means one lot of letters goes inside another.
'end of' suggests the final letters.
The final letter of 'term' is 'm'.
'oral' going around 'm' is 'ormal'.
'n'+'ormal'='NORMAL'
(Other definitions for normal that I've seen before include "Regular" , "Standard; at right angles" , "Usual, typical, expected" , "Usual, not extraordinary" , "'Usual, typical (6)'" .)