Photoreceptor cell (4)
'photoreceptor cell' is the definition.
(I know that cone is a type of photoreceptor cell)
This is the entire clue.
(Other definitions for cone that I've seen before include "Hollow object associated with ice cream and motorways" , "Something dropped from tree" , "Movable plastic bollard" , "Tapering shape" , "Solid figure" .)
'photoreceptor cell' is the definition.
(I know that rod is a type of photoreceptor cell)
This is the entire clue.
(Other definitions for rod that I've seen before include "Cane used for flogging" , "Long, straight stick" , "Fisherman's item" , "Angler's equipment" , "Stick; angler" .)