Awful conservatories scorned by seniors who really ham it up (7)
I believe the answer is:
overact
'ham it up' is the definition.
(as in a ham actor)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for overact that I've seen before include "Do what ham thespian does" , "Ham (on stage)" , "In part, fail to convince" , "Exaggeratedly perform a role" , "Be unsubtle on stage" .)