Settler's high supporting structure (7)
I believe the answer is:
trestle
'supporting structure' is the definition.
(trestle is a kind of supporting structure)
'settler's high' is the wordplay.
'high' is an anagram indicator (can mean drunk or on drugs and hence disordered).
'settler' anagrammed gives 'TRESTLE'.
(Other definitions for trestle that I've seen before include "Simple table support" , "Supporting structure for bridge or tabletop" , "Support for table top" , "Braced support" , "support of growth" .)