Detect hint of micronutrient (5,7)
I believe the answer is:
trace element
'micronutrient' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I don't see?
'detect hint' is the wordplay.
'detect' becomes 'trace' (I've seen this before).
'hint' becomes 'element' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'trace'+'element'='TRACE ELEMENT'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for trace element that I've seen before include "Constituent present in only small amounts" , "Chemical present in small quantities" .)