Sup tea Lucy brewed that's good for the cold (10)
I believe the answer is:
eucalyptus
'good for the cold' is the definition.
I can't judge whether this defines the answer.
'sup tea lucy brewed' is the wordplay.
'brewed' indicates anagramming the letters.
'sup'+'tea'+'lucy'='suptealucy'
'suptealucy' with letters rearranged gives 'EUCALYPTUS'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for eucalyptus that I've seen before include "Australian tree yielding gum and oil" , "Australasian tree" , "Evergreen tree" .)
