Steep charge supporting staff (8)
I believe the answer is:
macerate
'steep' is the definition.
(thesaurus)
'charge supporting staff' is the wordplay.
'charge' becomes 'rate' (rate is a kind of charge**).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'staff' becomes 'mace' (mace is a kind of staff).
'rate' after 'mace' is 'MACERATE'.
(Other definitions for macerate that I've seen before include "Steep in liquid like cream tea" , "Soak" , "Cream tea (anag) -- soften by steeping in liquid" , "Soften food by soaking" .)