Investigate doctor in Togo (2,4)
I believe the answer is:
go into
'investigate' is the definition.
(thesaurus)
'doctor in togo' is the wordplay.
'doctor' indicates anagramming the letters.
'in'+'togo'='intogo'
'intogo' with letters rearranged gives 'GO INTO'.
(Other definitions for go into that I've seen before include "Enter or investigate" , "Explore" , "Investigate or become a member" , "Enter or examine in depth" .)