Tea cake? Not entirely (6)
I believe the answer is:
gateau
'tea cake?' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for gateau that I've seen before include "rich food" , "Fancy cake" , "(French?) cake" , "Richly decorated cake" , "Cream dessert cake" .)