Note a ruler is very wet (7)
I believe the answer is:
soaking
'very wet' is the definition.
(I know that soaking is a more specific form of the attribute very wet)
'note a ruler' is the wordplay.
'note' becomes 'so' (musical note).
'ruler' becomes 'king' (king is a kind of ruler).
'so'+'a'+'king'='SOAKING'
'is' is the link.
(Other definitions for soaking that I've seen before include "Wet" , "Drenched" .)