Water casing of a samovar (4)
I believe the answer is:
saar
'water casing' is the definition.
The definition suggests a singular noun which matches the answer.
'a samovar' is the wordplay.
I cannot really see how this works, but
'a' is found in the answer.
The remaining letters 'sar' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for saar that I've seen before include "German wine valley" , "River of France and Germany" .)