Home before midnight then back to bar (5)
I believe the answer is:
ingot
'bar' is the definition.
(block of metal, eg a bar of gold)
'home before midnight then back to' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'before' says to put letters next to each other.
'midnight' becomes 'g' (the middle letter in 'night').
'then' means one lot of letters go next to another.
'back' is a reversal indicator.
'to' backwards is 'ot'.
'in'+'g'+'ot'='INGOT'
(Other definitions for ingot that I've seen before include "Block of, eg, gold" , "Mass of unwrought gold, for instance" , "A lump of metal, perhaps gold" , "Bar, often gold" , "Brick-shaped lump of cast metal" .)