Container where nectar is processed (8)
I believe the answer is:
'container' is the definition.
(canister is a kind of container)
'nectar is processed' is the wordplay.
'processed' is an anagram indicator.
'nectaris' is an anagram of 'CANISTER'.
'where' is the link.
(Other definitions for canister that I've seen before include "Metal container, for tea say", "Container for a film reel", "Jar (of e.g. tea, sugar)", "Container for e.g. tea", "Container for storing dry food".)