I am put in a ruined castle for a stretch maybe (7)
I believe the answer is:
elastic
'for a stretch maybe' is the definition.
(elastic things are designed to be stretched)
I don't understand the remainder of the clue.
(Other definitions for elastic that I've seen before include "Like some bands" , "Kind of band" , "Narrow band of rubber" , "capable of adapting to change?" , "Stuff that stretches to Castile" .)