Old King heading for European conflict in days (6)
I believe the answer is:
edward
'old king' is the definition.
(any of several kings called Edward)
'heading for european conflict in days' is the wordplay.
'heading for' says to take the initial letters.
'conflict' becomes 'war' (war is a kind of conflict).
'in' means one lot of letters goes inside another.
'days' becomes 'dd' (an abbreviation for day written twice).
The initial letter of 'european' is 'e'.
'war' put inside 'dd' is 'dward'.
'e'+'dward'='EDWARD'
(Other definitions for edward that I've seen before include "Male name" , "Elgar or Lear, for instance" , "Prince born in 1964" , "Sir -- Elgar, composer" , "The Black Prince's name" .)