Heated conflict beginning in March (4)
I believe the answer is:
warm
'heated' is the definition.
(I've seen this in another clue)
'conflict beginning in march' is the wordplay.
'conflict' becomes 'war' (war is a kind of conflict).
'beginning in' suggests taking the first letters.
The first letter of 'march' is 'm'.
'war'+'m'='WARM'
(Other definitions for warm that I've seen before include "showing enthusiasm" , "Passionate; ardent" , "Friendly" , "Intimate - with a comfortable temperature" , "Apply heat to" .)