Time to add sugar (6)
I believe the answer is:
season
'time' is the definition.
(a season is a period of time)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for season that I've seen before include "Flavour food with salt, pepper etc" , "Add flavour at a certain time of year" , "Spring, say" , "spring, perhaps" , "To dry (wood) for use as timber" .)