Stasi moved to hold American author (6)
I believe the answer is:
asimov
'american author' is the definition.
(sci-fi writer Isaac Asimov)
'stasi moved to hold' is the wordplay.
'to hold' says the answer is hidden in the clue (I've seen 'held' mean this).
'ASIMOV' is hidden in the letters of 'stasi moved'.
(Other definitions for asimov that I've seen before include "novelist" , "Author of "Three Laws of Robotics"" , "He wrote about robots" , "Isaac ---, SF author" , "Isaac --, science fiction author" .)