Curtains for Depeche Mode, after half the characters leave - book describes break up (5)
I believe the answer is:
demob
'break up' is the definition.
(thesaurus)
'curtains for depeche mode after half the characters leave book' is the wordplay.
'curtains for' means to remove the middle letters (the edge letters are curtains around the word).
'after half the characters leave' suggests halving the letters.
'book' becomes 'b'.
'depeche' with its middle removed is 'de'.
'mode' halved is 'mo'.
'de'+'mo'+'b'='DEMOB'
'describes' acts as a link.
(Other definitions for demob that I've seen before include "soldier's release" , "Briefly disband" , "stand down" , "Release from army" , "Discharge from forces" .)