Subjects about right: Cancer and Capricorn (7)
I believe the answer is:
tropics
'cancer and capricorn' is the definition.
(I've seen this in another clue)
'subjects about right' is the wordplay.
'subjects' becomes 'topics' ('topic' can be a synonym of 'subject').
'about' means one lot of letters goes inside another.
'right' becomes 'r' (common abbreviation).
'topics' going around 'r' is 'TROPICS'.
(Other definitions for tropics that I've seen before include "hot spots" , "Cancer, Capricorn" , "hot regions" , "Region either side of equator" , "hot spot" .)