Unattached (6)
'unattached' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for loose that I've seen before include "Untie; dissolute" , "Not bound" , "Not tightly fixed" , "released from confinement" , "easy with one's favours" .)
'unattached' is the definition.
(without a partner)
This is the entire clue.
(Other definitions for single that I've seen before include "Just one - on one's own" , "Ticket To Ride < : > hit" , "Not in a relationship" , "Unaccompanied" , "Unique" .)