Let go the clergy's morning dress by the sound of it (9)
I believe the answer is:
sackcloth
'morning dress by the sound of it' is the definition.
I can't tell whether this defines the answer.
'let go the clergy's' is the wordplay.
'let go' becomes 'sack' (let go can mean to sack someone from a job).
'the clergy' becomes 'cloth' (I've seen this before).
'sack'+'cloth'='SACKCLOTH'
Can you help me to learn more?
(Other definitions for sackcloth that I've seen before include "part of repentance" , "Old garment" , "In which penitent is" , "Penitent's attire" , "Penitential attire" .)