Land in contact with water - this, after storm, mostly a pulpy mess (7)
I believe the answer is:
isthmus
'land' is the definition.
(isthmus is a kind of land)
'contact with water this after storm mostly a pulpy mess' is the wordplay.
I cannot really understand how this works, but
an anagram of 'this' is 'isth' which is present in the answer.
The remaining letters 'mus' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for isthmus that I've seen before include "Narrow stretch of land joining two larger masses" , "Narrow strip of land connecting two larger areas" , "Narrow strip joining larger areas of land" , "Narrow strip of land connecting two larger land masses" , "This sum (anag)" .)