At large in empty space beside toilet (5)
I believe the answer is:
loose
'at large' is the definition.
(synonyms)
'empty space beside toilet' is the wordplay.
'empty' says to hollow out the word (remove centre letters).
'beside' is a charade indicator (letters next to each other) (I've seen this in other clues).
'toilet' becomes 'loo' (loo can informally mean a toilet).
'space' with its centre taken out is 'se'.
'se' put after 'loo' is 'LOOSE'.
'in' acts as a link.
(Other definitions for loose that I've seen before include "Imprecise" , "Lax or at large" , "Not tied up or attached" , "Unattached" , "At liberty" .)