Some purblind ring-tailed lemur (5)
I believe the answer is:
indri
'lemur' is the definition.
(indri is a kind of lemur)
'some purblind ring-tailed' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'INDRI' is hidden in the letters of 'purblind ring tailed'.
(Other definitions for indri that I've seen before include "large primate" , "Species of lemur" , "Madagascan mammal" , "Big Madagascan lemur" , "native of Madagascar" .)