Ugly expression as I'm introduced to class (7)
I believe the answer is:
grimace
'ugly expression' is the definition.
(I've seen this before)
'i'm introduced to class' is the wordplay.
'introduced to' is an insertion indicator.
'class' becomes 'grace' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'im' inserted into 'grace' is 'GRIMACE'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for grimace that I've seen before include "Twisted facial expression" , "Facial contortion expressive of pain or disgust" , "Express wry amusement" , "Smirk" , "look disgusted" .)