Enemy of distracted knight: mind will wander (8)
I believe the answer is:
windmill
'enemy of distracted knight' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'mind will wander' is the wordplay.
'wander' is an anagram indicator.
'mind'+'will'='mindwill'
'mindwill' anagrammed gives 'WINDMILL'.
Can you help me to learn more?
(Other definitions for windmill that I've seen before include "Wind generator" , "It extracts energy from moving air" , "Generator to extract energy from moving air" , "Natural energy generator" , "Source of green power" .)