Some having a tea, usually, and cake (6)
I believe the answer is:
gateau
'cake' is the definition.
(gateau is a kind of cake)
'some having a tea usually' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'GATEAU' can be found hidden inside 'having a tea usually'.
'and' is the link.
(Other definitions for gateau that I've seen before include "Rich dessert cake" , "named for Black Forest?" , "(French?) cake" , "Cream dessert cake" , "Richly decorated cake" .)