An educational expression? (4)
I believe the answer is:
term
'expression?' is the definition.
(both can mean a piece of vocabulary)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for term that I've seen before include "Academic period" , "Call" , "An expression or period in office" , "Name" , "Expression, or period in which law court holds sessions" .)