Rate carelessly and rip apart (4)
I believe the answer is:
tear
'rip apart' is the definition.
(I've seen this in another clue)
'rate carelessly' is the wordplay.
'carelessly' is an anagram indicator.
'rate' with letters rearranged gives 'TEAR'.
'and' is the link.
(Other definitions for tear that I've seen before include "Small flaw, as in glass" , "Rip the eye moistener?" , "Lacerate - sign of sorrow" , "Product of the lachrymal gland" , "A drop of sadness" .)