Feel kind about mammal (3)
I believe the answer is:
elk
'mammal' is the definition.
(elk is a kind of mammal)
'feel kind about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'ELK' is hidden within 'feel kind'.
(Other definitions for elk that I've seen before include "European moose" , "Fraternal American" , "Largest living deer" , "Type of moose" , "Wapiti" .)