Charge for spice is steep (8)
I believe the answer is:
macerate
'is steep' is the definition.
(thesaurus)
'charge for spice' is the wordplay.
'charge' becomes 'rate' (rate is a kind of charge**).
'for' means one lot of letters go next to another (I've seen this in other clues).
'spice' becomes 'mace' (mace is a kind of spice).
'rate' put after 'mace' is 'MACERATE'.
(Other definitions for macerate that I've seen before include "Soften food by soaking" , "Steep in liquid like cream tea" , "Cream tea (anag) -- soften by steeping in liquid" , "Soak" .)