Part of sentence pupils learn about in English at school? (7)
I believe the answer is:
subject
I believe this is a double definition.
'part of sentence pupils learn about' is the first definition.
(as in a grammatical subject)
'english at school?' is the second definition.
(school subject)
'in' is the link.
(Other definitions for subject that I've seen before include "UK citizen?" , "Branch of knowledge" , "Theme - one under rule" , "Theme (of a fugue)" , "What ruler is not" .)