Confused loser lost right to be alone (4)
I believe the answer is:
sole
'be alone' is the definition.
(synonyms)
'confused loser lost right' is the wordplay.
'confused' indicates anagramming the letters.
'lost' indicates named letters should be taken away.
'right' becomes 'r' (common abbreviation).
'loser' with 'r' taken away is 'lose'.
'lose' is an anagram of 'SOLE'.
'to' acts as a link.
(Other definitions for sole that I've seen before include "European flatfish" , "Fish - alone" , "A lone sort of fish - lose it" , "Exclusive class of fish" , "Kind of fish - lose it" .)