Spice up writer (5)
I believe the answer is:
sumac
'spice' is the definition.
(sumac is a spice)
'up writer' is the wordplay.
'up' is a reversal indicator (in down clue: letters go upwards).
'writer' becomes 'Camus' (author Albert Camus).
'camus' backwards is 'SUMAC'.
(Other definitions for sumac that I've seen before include "Smoke-bush" , "Small tree bright in autumn" , "Shrub or small tree - Camus (anag)" , "Rudely brief" , "Spice" .)