Something to crush mite (4)
I believe the answer is:
item
'something' is the definition.
(item means a thing)
'crush mite' is the wordplay.
'crush' indicates an anagram (I've seen 'crushed' mean this).
'mite' is an anagram of 'ITEM'.
'to' acts as a link.
(Other definitions for item that I've seen before include "Bit of information" , "Seperate article in an enumeration" , "Unit; detail" , "Romantic couple" , "Entry (in an account)" .)