Right to miss start of mock exam (4)
I believe the answer is:
oral
'mock exam' is the definition.
'oral' can be an answer for 'exam' (spoken academic test). I am unsure of the 'mock' bit.
'right to miss start' is the wordplay.
'right' becomes 'moral' (similar in meaning).
'to miss start' means to remove the first letter (I've seen 'missing start' mean this).
'moral' with its initial letter removed is 'ORAL'.
'of' is the link.
Can you help me to learn more?
(Other definitions for oral that I've seen before include "from the trap" , "Related to the mouth" , "Spoken exam" , "Mouth-related" , "Relating to the mouth - exam" .)