Seaweed split by united cast provided nutrition (9)
I believe the answer is:
nourished
'provided nutrition' is the definition.
'nourished' can be an answer for 'provided' (nourishing is a kind of providing). I am not certain of the 'nutrition' bit.
'seaweed split by united cast' is the wordplay.
I cannot quite see how this works, but
'united' could be 'u' (abbreviation as in Man U for Manchester United) and 'u' is present in the answer.
'seaweed' could be 'nori' (I've seen this before) and 'nori' is located in the leftover letters.
'cast' could be 'shed' (synonyms) and 'shed' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for nourished that I've seen before include "Sustained" , "properly fed" .)