To keep mum quiet, work or cease trading? (4,2,4)
I believe the answer is:
shut up shop
'cease trading?' is the definition.
(I've seen this before)
'to keep mum quiet work' is the wordplay.
'to keep mum' becomes 'shutup' ('shut up' can be a synonym of 'keep mum').
'quiet' becomes 'sh'.
'work' becomes 'op' (abbreviation for opus).
'shutup'+'sh'+'op'='SHUT UP SHOP'
'or' acts as a link.
(Other definitions for shut up shop that I've seen before include "Cease trading" , "Close business at end of day (or permanently)" .)