Machine-cut soap (5)
I believe the answer is:
lathe
'machine' is the definition.
(lathe is a kind of machine)
'cut soap' is the wordplay.
'cut' means to remove the last letter.
'soap' becomes 'lather' (synonyms).
'lather' with its last letter taken off is 'LATHE'.
(Other definitions for lathe that I've seen before include "Wood-shaping machine" , "Machine that turns wood or metal for cutting" , "Rotating machine tool" , "Turner's machine" , "piece of machinery" .)