Gamble when duke retreats, eliminated (4)
I believe the answer is:
iced
'retreats eliminated' is the definition.
I can't tell whether this definition defines the answer.
'gamble when duke' is the wordplay.
'gamble when' becomes 'ice' (I can't justify this - if you can you should give a lot more credence to this answer).
'duke' becomes 'd' (abbreviation).
'ice'+'d'='ICED'
(Other definitions for iced that I've seen before include "Chilled; decorated" , "despatched to American underworld" , "found thus in freezer?" , "Decorated; killed" , "Decorated with frosting" .)