Tom, maybe, with self-confidence increase in class (10)
I believe the answer is:
categorise
'class' is the definition.
(I know that categorise is the is a more specific form of the action of class.)
'tom maybe with self-confidence increase' is the wordplay.
'tom maybe' becomes 'cat' (a tom is a male cat).
'with' says to put letters next to each other.
'self confidence' becomes 'ego'.
'increase' becomes 'rise' (rising is a kind of increasing).
'cat'+'ego'+'rise'='CATEGORISE'
'in' is the link.
(Other definitions for categorise that I've seen before include "Classify" , "class" , "Sort" .)