Split right before finish (4)
I believe the answer is:
rend
'split' is the definition.
(rend can mean to split or tear)
'right before finish' is the wordplay.
'right' becomes 'r' (abbreviation).
'before' means one lot of letters go next to another.
'finish' becomes 'end' (synonyms).
'r'+'end'='REND'
(Other definitions for rend that I've seen before include "Tear apart roughly" , "Tear violently" , "Tear to pieces" , "Tear savagely" , "Rip" .)