Cream tea essentially low in calories (5)
I believe the answer is:
elite
'cream' is the definition.
(thesaurus)
'tea essentially low in calories' is the wordplay.
'essentially' means to look at the middle letters.
'low in calories' becomes 'lite' (I've seen this before).
The middle letter of 'tea' is 'e'.
'e'+'lite'='ELITE'
(Other definitions for elite that I've seen before include "twelve pitch in the office" , "Letter size; superior group" , "A privileged class of people" , "High society" , "First-class" .)