Climbing mount, see a stake (4)
I believe the answer is:
ante
'a stake' is the definition.
(ante is a kind of stake)
'climbing mount' is the wordplay.
'climbing' says the letters should be written backwards (in a down clue, letters climb up).
'mount' becomes 'etna' (Etna is an example).
'etna' in reverse letter order is 'ANTE'.
'see' is the link.
(Other definitions for ante that I've seen before include "early payment" , "Pay" , "Initial stake in a poker game" , "Prefix meaning before" , "Pre-deal stake" .)