Sang like chorister at home and harmonised (7)
I believe the answer is:
intoned
'sang like chorister' is the definition.
(intone can mean to sing or chant)
'home and harmonised' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'and' is a charade indicator (letters next to each other).
'harmonised' becomes 'toned' (I've seen this in another clue).
'in'+'toned'='INTONED'
'at' acts as a link.
(Other definitions for intoned that I've seen before include "Sang in church" , "Said flatly" , "Recited in chanting voice" , "sounded like the vicar?" , "Chanted" .)