Shock report finally appearing in tabloid (4)
I believe the answer is:
stun
'shock' is the definition.
(both can mean to surprise)
'report finally appearing in tabloid' is the wordplay.
'finally' indicates one should take the final letters.
'appearing in' means one lot of letters goes inside another.
'tabloid' becomes 'Sun' (The Sun, UK newspaper).
The last letter of 'report' is 't'.
't' going within 'sun' is 'STUN'.
(Other definitions for stun that I've seen before include "Leave speechless" , "Dumbfound" , "Knock into a semi-conscious state" , "Surprise greatly, knock someone''s socks off" , "Knock cold" .)