Poor person in shelter with old books (4-3)
I believe the answer is:
have-not
'poor person' is the definition.
('have-not' can be a synonym of 'poor person')
'shelter with old books' is the subsidiary indication.
'shelter' becomes 'haven' (haven is a kind of shelter).
'with' is a charade indicator (letters next to each other).
'old books' becomes 'ot' (Old Testament).
'haven'+'ot'='havenot'
'in' is the link.
(Other definitions for have-not that I've seen before include "Someone who lacks possessions" , "Deprived person" , "Economically disadvantaged person" , "Person of little material wealth" , "Someone with meagre possessions" .)