Hello Strangelybrown - I can answer two of your queries, but the "headwaiter" one is also puzzling me.
53 A is ICE (kill) + NI ("unit" without the outside letters)
55A is HR (human resources) + ALL D (entirely died) inside TOM (male).
The other two I can't fathom are:-
29 A - "Artist dividing using shade" (6) -R-I-H
and 32 D - "Watson's colleague lacking potassium about to have a bite to eat" - this looks like CREATIC, but I can't see where Watson's colleague fits in.