Cup of tea by lake followed by dessert (7)
I believe the answer is:
chalice
'cup' is the definition.
(chalice is a kind of cup)
'tea by lake followed by dessert' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'by' says to put letters next to each other.
'lake' becomes 'l'.
'followed by' is a charade indicator (letters next to each other).
'dessert' becomes 'ice' (ice is a kind of dessert**).
'cha'+'l'+'ice'='CHALICE'
'of' acts as a link.
(Other definitions for chalice that I've seen before include "cup used in company with host" , "Church vessel" , "Large goblet for consecrated wine" , "Necessity for communion" , "Communion cup" .)