Order nothing for soldier (8)
I believe the answer is:
commando
'soldier' is the definition.
(I know this)
'order nothing' is the wordplay.
'order' becomes 'command' (commanding is a kind of ordering).
'nothing' becomes 'O' (O resembles 0).
'command'+'o'='COMMANDO'
'for' acts as a link.
(Other definitions for commando that I've seen before include "Kilt-wearer might go" , "Soldier trained for raiding" , "Soldier trained to carry out dangerous raids" , "Soldier trained for carrying out raids" , "One soldier" .)