Careless Estonian's hit (9)
I believe the answer is:
sensation
'hit' is the definition.
(I've seen this in another clue)
'careless estonian's' is the wordplay.
'careless' indicates an anagram.
'estonians' with letters rearranged gives 'SENSATION'.
(Other definitions for sensation that I've seen before include "Feeling, awareness of stimulation" , "Awareness of a stimulus, such as heat or pain" , "Feeling produced by stimulation, or dramatic news (9)" , "Scandalous news item" , "Physical feeling or perception" .)