Extra maths procedure by a student (10)
I believe the answer is:
additional
'extra' is the definition.
(extra means additional)
'procedure by a student' is the wordplay.
'procedure' becomes 'addition' (addition is a kind of procedure).
'by' is a charade indicator (letters next to each other).
'student' becomes 'l' (as in L-plates for learner drivers).
'addition'+'a'+'l'='ADDITIONAL'
'maths' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for additional that I've seen before include "Extra" , "with sums, perhaps" .)