John has master's weaving equipment (4)
I believe the answer is:
loom
'weaving equipment' is the definition.
(apparatus for weaving)
'john has master's' is the wordplay.
'john' becomes 'loo' (loo is a kind of john).
'has' means one lot of letters go next to another.
'master' becomes 'm'.
'loo'+'m'='LOOM'
(Other definitions for loom that I've seen before include "Bulk large" , "Textile machine for weaving" , "Come into view" , "Apparatus for weaving cloth" , "menacing" .)