Every sort of grey sensitivity (7)
I believe the answer is:
allergy
'sensitivity' is the definition.
(allergy is a kind of sensitivity)
'every sort of grey' is the wordplay.
'every' becomes 'all' ('all' can be similar in meaning to 'every').
'sort of' indicates an anagram.
'grey' with letters rearranged gives 'ergy'.
'all'+'ergy'='ALLERGY'
(Other definitions for allergy that I've seen before include "Bad immune system response" , "Strong aversion" , "Largely in an unfavourable reaction, maybe to pollen" , "Hypersensitive reaction to certain substances" , "Antigen sensitivity" .)