Cost to support club is steep (8)
I believe the answer is:
macerate
'is steep' is the definition.
(both can mean to soak in a liquid)
'cost to support club' is the wordplay.
'cost' becomes 'rate' (rate is a kind of cost).
'to support' is a charade indicator (letters next to each other) (in a down clue, some letters hold others up).
'club' becomes 'mace' (I've seen this before).
'rate' put after 'mace' is 'MACERATE'.
(Other definitions for macerate that I've seen before include "Cream tea (anag) -- soften by steeping in liquid" , "Steep in liquid like cream tea" , "Soften food by soaking" , "Soak" .)