A certain area of literature (5)
I believe the answer is:
tract
'a certain area' is the definition.
'tract' can be an answer for 'area' (tract is a kind of area). I'm not certain of the 'a certain' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for tract that I've seen before include "Pamphlet; area of land" , "Large area; pamphlet" , "Stretch of land or religious pamphlet" , "anthem" , "Extensive area of land" .)