Stunt involving feta (4)
I believe the answer is:
feat
'stunt' is the definition.
(I've seen this in another clue)
'involving feta' is the wordplay.
'involving' indicates an anagram.
'feta' with letters rearranged gives 'FEAT'.
(Other definitions for feat that I've seen before include "Notable act" , "Remarkable achievement of fate" , "Notable achievement" , "Deed; achievement" , "Significant achievement" .)