A bit detached (5)
I believe the answer is:
apart
'detached' is the definition.
(synonyms)
'a bit' is the wordplay.
'bit' becomes 'part' (both can mean a piece of something).
'a'+'part'='APART'
(Other definitions for apart that I've seen before include "Separate in a trap" , "Asunder" , "Isolated" , "Separated or at a distance" , "Unconnected" .)