Repentant writer, one needing shelter (8)
I believe the answer is:
penitent
'repentant' is the definition.
('penitent' can be a synonym of 'repentant')
'writer one needing shelter' is the wordplay.
'writer' becomes 'pen' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'needing' says to put letters next to each other.
'shelter' becomes 'tent' (tent is a kind of shelter).
'pen'+'i'+'tent'='PENITENT'
(Other definitions for penitent that I've seen before include "Expressing sorrow for one's sins" , "Feeling remorse" , "Rueful" , "Feeling regret for one's sins" , "Regretting one's wrongdoings" .)