Take a break about one then have another go at the exam perhaps (5)
I believe the answer is:
resit
'have another go at the exam perhaps' is the definition.
I can't tell whether this defines the answer.
'take a break about one' is the wordplay.
'take a break' becomes 'rest' (to have a rest is to take a break).
'about' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'rest' placed around 'i' is 'RESIT'.
'then' is the link.
Can you help me to learn more?
(Other definitions for resit that I've seen before include "later exam" , "repeated test" , "Student's test" , "take another exam" , "second exam" .)