Medical approach that’s treated gland in the eye? Yes and no (6,7)
I believe the answer is:
dental hygiene
'medical approach' is the definition.
The definition suggests a singular noun which matches the answer.
'treated gland in the eye? yes and no' is the wordplay.
'gland in the eye' anagrams to 'DENTAL HYGIENE'.
Though, I'm not clear how this is indicated.
'that's' is the link.
Can you help me to learn more?
(Other definitions for dental hygiene that I've seen before include "Prophylactic treatment" , "Cleaning one's teeth etc" .)