Update devotional book? (6)
I believe the answer is:
rework
'update' is the definition.
(rework can mean to update something)
'devotional book?' is the wordplay.
'devotional' becomes 're' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'book?' becomes 'work' (book is a kind of work).
're'+'work'='REWORK'
(Other definitions for rework that I've seen before include "Fashion again" , "What editors do" , "Alter, revise" .)