Abstruse; indistinct (7)
I believe the answer is:
obscure
I believe this is a double definition.
'abstruse' is the first definition.
(synonyms)
'indistinct' is the second definition.
(I've seen this before)
(Other definitions for obscure that I've seen before include "Dim, indistinct or not well known" , "Unsung" , "Not clear, indistinct" , "Little known - dark" , "Blot out" .)