Regularly – often – tea is cheese (4)
I believe the answer is:
feta
'is cheese' is the definition.
(type of cheese)
'regularly often tea' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'often'+'tea'='oftentea'
The alternating letters of 'oftentea' are 'FETA'.
(Other definitions for feta that I've seen before include "Crumbly Greek cheese" , "10 down cheese" , "Low-fat cheese" , "A ewe's, goat's milk cheese" , "Soft Greek cheese" .)