Dish sponge blocking drain too regularly (7)
I believe the answer is:
risotto
'dish' is the definition.
(risotto is a kind of dish)
'sponge blocking drain too regularly' is the wordplay.
'sponge' becomes 'sot' (I've seen this in another clue).
'blocking' means one lot of letters goes inside another.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'drain'+'too'='draintoo'
The alternating letters of 'draintoo' are 'rito'.
'sot' placed inside 'rito' is 'RISOTTO'.
(Other definitions for risotto that I've seen before include "scoff" , "Italian course" , "Main course" , "You cook it in stock" , "Rice/stock dish" .)