Tot sees doctor before noon (4)
I believe the answer is:
dram
'tot' is the definition.
(thesaurus)
'doctor before noon' is the wordplay.
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'before noon' becomes 'am'.
'dr'+'am'='DRAM'
'sees' is the link.
(Other definitions for dram that I've seen before include "Apothecary's weight, 60 grains" , "Measure of spirits" , "Small drink of alcohol" , "Small drink of spirits" , "Small drink of whisky" .)