Penetrate chapter shunned by middle of America (5)
I believe the answer is:
enter
'penetrate' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for enter that I've seen before include "Fill in" , "Come in - register" , "Fruit drink" , "Come in - penetrate - record" , "Break in" .)