Hazel's devoted fan?
I believe the answer is:
nut
This clue might be a double definition.
'hazel's' is the first definition.
The definition and answer can be both plants as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'devoted fan?' is the second definition.
(I've seen this in another clue)
Can you help me to learn more?
(Other definitions for nut that I've seen before include "Vegetarian food" , "Enthusiastic person" , "eg Almond, brazil" , "Screwing block" , "One securing bolt" .)