Emotionally distant (5)
'emotionally distant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aloof that I've seen before include "Withdrawn, distant" , "Blood deficiency" , "Showing detached attitude" , "Remote, distant" , "rather cold" .)
(Other definitions for cold that I've seen before include "Unfriendly" , "Chilly; unemotional" , "Biting" , "Common ailment" , "Stand-offish" .)