Worry, needing chapter for book? That's a bummer (6)
I believe the answer is:
cadger
'that's a bummer' is the definition.
(thesaurus)
I don't understand the rest of the clue.
(Other definitions for cadger that I've seen before include "Sponger" , "Scrounger, moocher" , "One who scrounges and begs" , "Graced (anag)" , "Scrounger seeking help" .)