Returning, Lib allowed into soldier’s lodging (6)
I believe the answer is:
billet
'soldier's lodging' is the definition.
(I've seen this before)
'returning lib allowed' is the wordplay.
'returning' is a reversal indicator.
'allowed' becomes 'let' (to let is to allow or permit).
'lib' back-to-front is 'bil'.
'bil'+'let'='BILLET'
'into' is the link.
(Other definitions for billet that I've seen before include "Piece of wood - bar of metal - place to stay" , "Requisitioned accommodation" , "Soldier's lodgings" , "Military lodging - little note" , "Lodgings for troops or evacuees" .)