Contest expected by left (4)
I believe the answer is:
duel
'contest' is the definition.
(thesaurus)
'expected by left' is the wordplay.
'expected' becomes 'due' (I've seen this before).
'by' means one lot of letters go next to another.
'left' becomes 'l' (common abbreviation).
'due'+'l'='DUEL'
(Other definitions for duel that I've seen before include "battle" , "Two-person combat" , "Fight over a point of honour" , "Fight to the death between two people" , "Single combat" .)