Some otters at zoo may be artificial (6)
I believe the answer is:
ersatz
'be artificial' is the definition.
('ersatz' can be similar in meaning to 'artificial')
'some otters at zoo' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ERSATZ' can be found hidden inside 'otters at zoo'.
'may' acts as a link.
(Other definitions for ersatz that I've seen before include "Imitation (from Ger.)" , "Substitute - fake" , "unnatural" , "Cheap substitute or imitation" , "Phoney as in Germany" .)