Reddish-brown (5)
'reddish-brown' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sepia that I've seen before include "Colour of old photographs" , "A greyish brown" , "brownish colour" , "Shade of brown, as in old photographs" , "Sort of drawing" .)
(Other definitions for rusty that I've seen before include "(Of iron) affected by damp" , "Behind the times" , "Impaired through lack of use" , "showing sign of inactivity?" , "Stiff with age" .)
'reddish-brown' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for chestnut that I've seen before include "Stale joke or cliche" , "Item for stuffing" , "Wooden" , "Tree (horse or sweet)" , "not a cracker!" .)
(Other definitions for mahogany that I've seen before include "Reddish-brown hardwood" , "Type of wood" , "Hard tropical wood used in making furniture" , "Tropical timber" , "tree" .)