Your items getting rearranged by poltergeists ultimately? Very curious (10)
I believe the answer is:
mysterious
'very curious' is the definition.
'your items getting rearranged by poltergeists ultimately?' is the wordplay.
'getting rearranged' is an anagram indicator.
'by' means one lot of letters go next to another.
'ultimately?' says to take the final letters (I've seen 'ultimately' mean this).
The last letter of 'poltergeists' is 's'.
'your'+'items'='youritems'
'youritems' anagrammed gives 'mysteriou'.
'mysteriou'+'s'='MYSTERIOUS'
(Other definitions for mysterious that I've seen before include "Enigmatic, baffling" , "Strange" , "Cryptic - baffling" , "Inexplicable" , "Secret" .)