Colour conflict in southeastern pottery (9)
I believe the answer is:
Here is my best explanation:
'pottery' is the definition.
'colour conflict in southeastern' is the subsidiary indication.
'colour' becomes 'tone' (tone is a kind of colour**).
'conflict' becomes 'war' (war is a kind of conflict).
'in' means one lot of letters goes inside another.
'southeastern' becomes 'se'.
'tonewar' inserted into 'se' is 'stoneware'.
(Other definitions for stoneware that I've seen before include "collection of pottery", "Pottery" and "Type of pottery".)