Vegetarian's taboo (4)
I believe the answer is:
meat
'vegetarian's taboo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for meat that I've seen before include "Ham, pork, chicken etc" , "Eg, beef or pork" , "The flesh of animals as food" , "Food for carnivores" , "17 [ESSENCE]" .)