Crikey, wild hogs! (4)
I believe the answer is:
gosh
'crikey' is the definition.
(I've seen this before)
'wild hogs' is the wordplay.
'wild' indicates anagramming the letters.
'hogs' with letters rearranged gives 'GOSH'.
(Other definitions for gosh that I've seen before include "English infirmary" , "I'm amazed!" , "Crikey" , "Good heavens!" , "Christmas" .)