Rearranging attic, I can be a schemer (9)
I believe the answer is:
tactician
'a schemer' is the definition.
(thesaurus)
'rearranging attic i can' is the wordplay.
'rearranging' indicates an anagram (I've seen 'rearranged' mean this).
'attic'+'i'+'can'='atticican'
'atticican' anagrammed gives 'TACTICIAN'.
'be' acts as a link.
(Other definitions for tactician that I've seen before include "General" , "Smart mover" , "One planning" , "One deploying forces in war" , "Adroit manoeuvrer" .)