Like certain atoms in air probed by a learner after university (9)
I believe the answer is:
univalent
'like certain atoms in air probed by a learner after university' is the definition.
I can't judge whether this definition defines the answer.
'in air probed by a learner after university' is the wordplay.
'in air' becomes 'vent' (both can mean to express or reveal. I am not sure about the 'in' bit.).
'probed by' is an insertion indicator (probe can mean to poke or prod into).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'after' means one lot of letters go next to another.
'university' becomes 'uni' (informal abbreviation).
'a'+'l'='al'
'vent' going around 'al' is 'valent'.
'valent' after 'uni' is 'UNIVALENT'.
Can you help me to learn more?
(Other definitions for univalent that I've seen before include "Capable of particular combination" , "Able to bond only once" .)