Instance, example (4)
I believe the answer is:
case
I believe this clue is a double definition.
'instance' is the first definition.
(synonyms)
'example' is the second definition.
(case can mean an example or instance of something)
(Other definitions for case that I've seen before include "Court evidence" , "Legal action; container" , "jacket, for example" , "Item of luggage" , "Police investigation" .)