Someone changing their locks? Sounds terrible! (4)
I believe the answer is:
dyer
'someone changing their locks?' is the definition.
I can't judge whether this defines the answer.
'sounds terrible' is the wordplay.
'sounds' shows a homophone (sound like).
'terrible' becomes 'dire' (synonyms).
'dire' sounds like 'DYER'.
Can you help me to learn more?
(Other definitions for dyer that I've seen before include "Fabric colourer" , "One changing colour" , "colourist" , "Cloth worker" , "Drey (anag.)" .)