Neglected old  shack on the far side of Argyll unnoticed by everyone at an early stage is a relic from Scotland’s past

 

Neglected = anagram indicator 
              O = old
     shack = Anagram fodder 
on the far side of = end letter selection indicator 
              Argyll   = provides L the final letter 
unnoticed by everyone = source of three remaining first letters 
at an early stage = first letter selection indicator 
                       is  = linkword 
a relic from Scotland's past = definition 
Neglected shuffles the word and letters to provide answer which is a Black House