Son having slight temperature avoids paella flavouring (7)
I believe the answer is:
'paella flavouring' is the definition.
(spice used for flavouring a paella)
I don't understand how the rest of the clue works.
(Other definitions for saffron that I've seen before include "Flavouring derived from a species of crocus" , "Spice from crocus" , "Type of crocus" , "Culinary spice" , "Orange-yellow colour" .)