A stake in a buoyant economy (4)
I believe the answer is:
ante
'a stake' is the definition.
(stake in poker)
'in a buoyant economy' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ANTE' is hidden within 'buoyant economy'.
(Other definitions for ante that I've seen before include "Opening bet" , "Hoofed mammal" , "Initial bet" , "Stake (that may be upped?)" , "Stake put up before the deal" .)