Dried fruit Ailsa regularly fed to cats and dogs? (6)
I believe the answer is:
raisin
'dried fruit' is the definition.
(raisin is a kind of dried fruit)
'ailsa regularly fed to cats and dogs?' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'fed to' is an insertion indicator.
'cats and dogs?' becomes 'rain' (I've seen this before).
The alternate letters of 'ailsa' are 'is'.
'is' inserted within 'rain' is 'RAISIN'.
(Other definitions for raisin that I've seen before include "Somewhat dry fruit" , "Cultivating" , "Dried grape used in cakes" , "A dried grape, nice in cake" , "sultana, say" .)