Brown shade (5)
(Other definitions for sepia that I've seen before include "Brown tone associated with old photographs" , "Brown pigment produced from cuttlefish ink" , "Sort of drawing" , "brownish colour" , "Brown of old photos" .)
'brown shade' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for umber that I've seen before include "Dark to reddish brown" , "Yellowish-brown pigment" , "Deep brown" , "Brown earthy substance used as pigment" , "Natural pigment" .)