Get rid of mould (4)
I believe the answer is:
cast
This clue is a double definition.
'get rid of' is the first definition.
(thesaurus)
'mould' is the second definition.
('cast' can be a synonym of 'mould')
(Other definitions for cast that I've seen before include "pitch" , "Personnel in a play" , "Squint to see" , "Pot" , "Throw the actors' group" .)