Orange tuber (3)
'orange tuber' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for yam that I've seen before include "American sweet potato" , "US sweet-potato" , "Potato-like vegetable" , "May be a sweet potato" , "May be a foreign potato" .)
(Other definitions for sweet potato that I've seen before include "South American vegetable" , "Edible tuber" , "Slightly sugary root vegetable" , "Yam-like vegetable" , "Tropical root vegetable" .)