Finish second highest (4)
I believe the answer is:
stop
'finish' is the definition.
(I know that finish can be written as stop)
'second highest' is the wordplay.
'second' becomes 's' (common abbreviation).
'highest' becomes 'top' (at the top).
's'+'top'='STOP'
(Other definitions for stop that I've seen before include "Quit" , "Part of organ" , "Red light signal" , "Knock out" , "Blockage" .)