Adds zest to (6)
'adds zest to' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Another definition for livens that I've seen is " Invigorates".)
(Other definitions for spices that I've seen before include "Cinnamon, cardamom etc" , "Substances that flavour food" , "Pungent food additives" , "They add zest, to food or life" , "Food flavour enhancers" .)