Wade and see shifting kelp (7)
I believe the answer is:
seaweed
'kelp' is the definition.
(I've seen this before)
'wade and see shifting' is the wordplay.
'and' says to put letters next to each other.
'shifting' indicates an anagram.
'wade' after 'see' is 'seewade'.
'seewade' is an anagram of 'SEAWEED'.
(Other definitions for seaweed that I've seen before include "water plant" , "Eg, kelp" , "Marine alga" , "Marine plant" , "what's been washed up" .)