The rustic lad was in disarray! (5)
I believe the answer is:
swain
'the rustic lad' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'was in disarray' is the wordplay.
'disarray' indicates an anagram.
'was'+'in'='wasin'
'wasin' anagrammed gives 'SWAIN'.
Can you help me to learn more?
(Other definitions for swain that I've seen before include "Male admirer" , "Beau" , "Country boy" , "Old word for young lover" , "Young lover (poet.)" .)