Act it out in the loft (5)
I believe the answer is:
'the loft' is the definition.
'act it out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'actit' anagrammed gives 'ATTIC'.
'in' acts as a link.
(Other definitions for attic that I've seen before include "Upper chamber" , "of Greek region" , "High level of" , "Loft room" , "room with lots of junk?" .)