Seaweeds tangled up in a gale (5)
I believe the answer is:
algae
'seaweeds' is the definition.
(I've seen this before)
'tangled up in a gale' is the wordplay.
'tangled up in' indicates anagramming the letters.
'a'+'gale'='agale'
'agale' with letters rearranged gives 'ALGAE'.
(Other definitions for algae that I've seen before include "Primitive organisms" , "Stemless water plants found in a gale" , "Water plants seen in a gale" , "Type of seaweed" , "Seaweeds etc" .)