Cordial start of meeting after hostilities (4)
I believe the answer is:
warm
'cordial' is the definition.
(similar in meaning)
'start of meeting after hostilities' is the wordplay.
'start of' indicates taking the first letters.
'after' says to put letters next to each other.
'hostilities' becomes 'war' (hostilities between two nations).
The first letter of 'meeting' is 'm'.
'm' put after 'war' is 'WARM'.
(Other definitions for warm that I've seen before include "On the brink of making discovery" , "Having moderate heat" , "Neither hot nor cold" , "Slightly hot" , "Moderately hot" .)