Remnants of wine found in old ewers periodically (4)
I believe the answer is:
lees
'remnants of wine' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'old ewers periodically' is the wordplay.
'periodically' indicates alternate letters (letters must be selected 'every so often').
'old'+'ewers'='oldewers'
The alternate letters of 'oldewers' are 'LEES'.
'found in' acts as a link.
Can you help me to learn more?
(Other definitions for lees that I've seen before include "Sediement or else" , "Dregs left by eels" , "Sediment from alcoholic drink" , "Dregs, sediment" , "worst part" .)