Small shake will do for window curtain (4)
I believe the answer is:
swag
'window curtain' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'small shake' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'shake' becomes 'wag' (synonyms).
's'+'wag'='SWAG'
'will do for' acts as a link.
Can you help me to learn more?
(Other definitions for swag that I've seen before include "Part of a curtain" , "hot property" , "goods from burglary" , "Booty, loot" , "bundle of possessions" .)