Something a pupil may do (6)

I believe the answer is:
dilate
'do' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how they can define each other.
'something a pupil' is the wordplay.
I cannot quite see how this works, but
'a' is present in the answer.
'pupil' could be 'l' (as in a learner driver with L-plates on their car) and 'l' is present in the answer.
'something' could be 'it' (both can refer to an object) and 'it' is found within the remaining letters.
The remaining letters 'de' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'may' acts as a link.
Can you help me to learn more?
(Other definitions for dilate that I've seen before include "Tailed (anag)" , "Expand - talk at length" , "Make wider or larger" , "Make (something) wider or more open" , "Widen, spread out" .)
