Clue: Extremes of lethargy with taking English in? With which Eng. Lit. students are familiar (6)
Answer: LYCEUM
Explanation: Definition: With which Eng. Lit. students are familiar
[*extremes of*] **L**(etharg)**Y** + **CUM** ("with") *taking* **E** (English) *in* 
 
 
*Lyceum can mean "a place devoted to literary studies"