One struggling to go through: nearly all at stake (9)
I believe the answer is:
combatant
'one struggling' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'go through nearly all at stake' is the wordplay.
'go through' becomes 'comb' (I can't justify this - if you can you should give a lot more credence to this answer).
'nearly all' means to remove the last letter.
'stake' becomes 'ante' (stake in poker).
'at'+'ante'='atante'
'atante' with its final letter taken off is 'atant'.
'comb'+'atant'='COMBATANT'
'to' is the link.
Can you help me to learn more?
(Other definitions for combatant that I've seen before include "Fighter" , "One engaged in fighting" , "Belligerent" , "Person engaged in fighting" , "Soldier" .)