A Maine resort with a lack of vitality (7)
I believe the answer is:
anaemia
'lack of vitality' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'a maine resort with a' is the wordplay.
'resort with' indicates anagramming the letters.
'maine' with its letters anagrammed with 'a' can make 'naemia'.
'a'+'naemia'='ANAEMIA'
Can you help me to learn more?
(Other definitions for anaemia that I've seen before include "Lack of red corpuscles in blood resulting in weakness" , "Bloodlessness" , "Red blood cell deficiency" , "Blood disorder -- ie I am Ana (anag)" , "Llama relative, its wool" .)