It goes up before the tax (5)
I believe the answer is:
tithe
'tax' is the definition.
(historical tax paid to the church)
'it goes up before the' is the wordplay.
'goes up' shows that the letters should be reversed in order.
'before' is a charade indicator (letters next to each other).
'it' written backwards gives 'ti'.
'ti'+'the'='TITHE'
(Other definitions for tithe that I've seen before include "Tenth of income given to church" , "Offering" , "Levy by church, e.g." , "One tenth - old church tax" , "It used to decimate income" .)