Landlord certain to include question about commencement of insurance (6)
I believe the answer is:
squire
'landlord' is the definition.
(thesaurus)
'certain to include question about commencement of insurance' is the wordplay.
'certain' becomes 'sure' (synonyms).
'to include' indicates putting letters inside.
'question' becomes 'q'.
'about' is an insertion indicator.
'commencement of' indicates taking the first letters.
The first letter of 'insurance' is 'i'.
'sure' enclosing 'q' is 'squre'.
'squre' going around 'i' is 'SQUIRE'.
(Other definitions for squire that I've seen before include "English country landowner" , "Country gentleman" , "Chief landowner of an area" , "Local landowner; knight's attendant" , "Old landowner" .)