Swish vessel less ordinary (4)
I believe the answer is:
cane
'swish' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'vessel less ordinary' is the wordplay.
'vessel' becomes 'can' (I've seen this before).
'less ordinary' becomes 'e' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'can'+'e'='CANE'
Can you help me to learn more?
(Other definitions for cane that I've seen before include "Strong, flexible stem" , "Slender stem of bamboo etc" , "e.g. Bamboo stem" , "Strong stem for to allow a plant to climb" , "Slender support, for 32 across say" .)