Book set in Waterloo Rd, Erith (5)
I believe the answer is:
order
'book' is the definition.
(order book is a kind of book)
'set in waterloo rd erith' is the wordplay.
'set in' says the answer is hidden in the clue.
'ORDER' can be found hidden inside 'waterloo rd erith'.
(Other definitions for order that I've seen before include "It could be the usual" , "Right arrangement" , "Ruling" , "Decree" , "Command; sequence" .)