Take a split second to correct mark (4)
I believe the answer is:
tick
'mark' is the definition.
(I've seen this before)
'take a split second to correct' is the wordplay.
I cannot quite see how this works, but
'second' could be 'tic' (tic or tick can mean a short amount of time) and 'tic' is located in the answer.
A single letter 'k' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tick that I've seen before include "sign of approval from teacher" , "Check mark" , "Credit; clock sound" , "Objectionable person" , "Mark correct, parasite" .)