Shed, old ramshackle hut by river (8)
I believe the answer is:
outhouse
'shed' is the definition.
(thesaurus)
'old ramshackle hut by river' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'ramshackle' indicates an anagram (I've seen this in other clues).
'by' says to put letters next to each other.
'river' becomes 'ouse' (Yorkshire river**).
'hut' is an anagram of 'uth'.
'o'+'uth'+'ouse'='OUTHOUSE'
(Other definitions for outhouse that I've seen before include "Shed or barn belonging to house but not part of it" , "Smaller building separate from main one" , "Construction" , "Building near home" , "Building in the grounds of a house" .)