Regularly excel with displays for cakes (7)
I believe the answer is:
eclairs
'cakes' is the definition.
(eclair is a type of cake)
'regularly excel with displays' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'with' means one lot of letters go next to another.
'displays' becomes 'airs' (air can mean to show or display).
The alternate letters of 'excel' are 'ecl'.
'ecl'+'airs'='ECLAIRS'
'for' acts as a link.
(Other definitions for eclairs that I've seen before include "Cream cakes" , "Oblong cream puffs" , "Elongated cream puffs" , "in which la creme may be found?" , "sticky fingers" .)