Regularly met, like a hoofed mammal (3)
I believe the answer is:
elk
'a hoofed mammal' is the definition.
(elk is a kind of hoofed mammal)
'regularly met like' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'met'+'like'='metlike'
The alternate letters of 'metlike' are 'ELK'.
(Other definitions for elk that I've seen before include "Big deer" , "Wapiti" , "American animal" , "Large ruminant" , "Fraternal American" .)