Cuttlefish (5)
I believe the answer is:
sepia
'cuttlefish' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sepia that I've seen before include "Brown of old photos" , "Reddish brown -- ie sap (anag)" , "Brown tint" , "Pigment obtained from cuttlefish ink" , "Old drawing" .)