Each swede spread outside as a plant (7)
I believe the answer is:
seaweed
'a plant' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'each swede spread outside' is the wordplay.
'each' becomes 'ea' (abbreviation).
'spread' indicates anagramming the letters.
'outside' indicates putting letters inside.
'swede' is an anagram of 'sweed'.
'ea' put into 'sweed' is 'SEAWEED'.
'as' is the link.
Can you help me to learn more?
(Other definitions for seaweed that I've seen before include "We eased (anag)" , "Main plant" , "Eg, kelp" , "Wrack" , "what's been washed up" .)