Scientist from site oddly imprisoned by a German twice (8)
I believe the answer is:
einstein
'scientist' is the definition.
(Einstein is an example)
'site oddly imprisoned by a german twice' is the wordplay.
'oddly' means one should take alternating letters.
'imprisoned by' is an insertion indicator.
'a german' becomes 'ein' ('a' in German).
'twice' shows that letters should be duplicated.
The alternate letters of 'site' are 'st'.
'ein' duplicated is 'einein'.
'st' put inside 'einein' is 'EINSTEIN'.
'from' is the link.
(Other definitions for einstein that I've seen before include "Nobel prize-winner" , "who strove for world peace" , "Albert -, relativity physicist" , "Disney's 14 [GREAT DANE]" , "Albert -, Nobel prize scientist" .)