Exam may once more be attempted initially in break (5)
I believe the answer is:
resat
'exam may once more' is the definition.
I can't judge whether this definition defines the answer.
'attempted initially in break' is the wordplay.
'initially' says to take the initial letters.
'in' means one lot of letters goes inside another.
'break' becomes 'rest' (resting is a kind of breaking**).
The first letter of 'attempted' is 'a'.
'a' placed into 'rest' is 'RESAT'.
'be' acts as a link.
Can you help me to learn more?
(Other definitions for resat that I've seen before include "Took another chance to pass" , "did test again" , "was tested again" , "Tried to pass again" , "went back to the paper" .)