Wallflower has to wither in good shade (9,6)
I believe the answer is:
shrinking violet
'wallflower' is the definition.
(both can mean a shy person)
'to wither in good shade' is the wordplay.
I cannot really see how this works, but
'wither' could be 'shrink' (synonyms) and 'shrink' is present in the answer.
'in' is present in the answer.
'good' could be 'g' (abbreviation) and 'g' is present in the answer.
'shade' could be 'violet' (I've seen this before) and 'violet' is located in the answer.
No letters remain.
This explanation may well be incorrect...
'has' acts as a link.
Can you help me to learn more?
(Other definitions for shrinking violet that I've seen before include "wallflower" , "Exaggeratedly shy person" , "Plant not growing" , "Person not likely to stand out" , "shy type" .)