Strong temporary accommodation established by river (6)
I believe the answer is:
potent
'strong' is the definition.
('potent' can be a synonym of 'strong')
'temporary accommodation established by river' is the wordplay.
'temporary accommodation' becomes 'tent' (I've seen this before).
'established by' says to put letters next to each other.
'river' becomes 'po' (Italian river).
'tent' put after 'po' is 'POTENT'.
(Other definitions for potent that I've seen before include "Intoxicating" , "Concentrated or strong, like liquor" , "Strong or concentrated, like some drink" , "Strong in operation" , "Forceful" .)