Proceed with fifth maths problem maybe after class (6)
I believe the answer is:
resume
'proceed with fifth maths' is the definition.
'resume' can be an answer for 'proceed' (I've seen this before). I'm unsure of the 'with fifth maths' bit.
'problem maybe after class' is the wordplay.
'problem' becomes 'sum' (arithmetic problem).
'maybe' becomes 'e' (I can't justify this - if you can you should give a lot more credence to this answer).
'after' is a charade indicator (letters next to each other).
'class' becomes 'RE' (Religious Education, school subject).
'sum'+'e'='sume'
'sume' after 're' is 'RESUME'.
Can you help me to learn more?
(Other definitions for resume that I've seen before include "Precis" , "Speak again" , "Continue after pause" , "Continue after interruption" , "Start again having taken a break" .)