Shelf giving first of lodgers advantage (5)
I believe the answer is:
ledge
'shelf' is the definition.
(I know that shelf can be written as ledge)
'giving first of lodgers advantage' is the wordplay.
'giving' says to put letters next to each other.
'first of lodgers' becomes 'l' (1st letter of 'lodgers').
'advantage' becomes 'edge' (having the edge is having an advantage).
'l' next to 'edge' is 'LEDGE'.
(Other definitions for ledge that I've seen before include "Narrow projecting shelf, on cliff or building" , "Submerged underwater shelf" , "Surface under e.g. window" , "Projecting shelf, horizontal projection" , "Shelf-life projection" .)