Clue: Timeless, warmer, quiet composition of Britten? (3,7)
Answer: WAR REQUIEM
Explanation: Definition: composition 
An anagram ('composition' doing double duty, unless you allow just 'of Britten' as the definition) of 'warmer quie[t]' minus the T ('timeless'). An answer in last week's Everyman was (First World War poet Wilfred) OWEN; in the War Requiem, Britten sets some of his poems interspersed with the Latin Requiem.