Payment before mountain ascent (4)
I believe the answer is:
ante
'payment' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ante that I've seen before include "Pay" , "Preceding birth" , "'Behind, before (4)'" , "Money put at risk" , "Money for poker" .)