Astronomer moved cornices up (10)
I believe the answer is:
copernicus
'astronomer' is the definition.
(I've seen this before)
'moved cornices up' is the wordplay.
'moved' indicates an anagram.
'cornices'+'up'='cornicesup'
'cornicesup' is an anagram of 'COPERNICUS'.
(Other definitions for copernicus that I've seen before include "Famous Prussian" , "Polish scholar" , "Polish astronomer d. 1543" , "16th century astronomer" , "He said we move in a ring" .)