Crossword Genius

King perhaps was concerned with English loss (4)

Ross

I believe the answer is:

card

'king perhaps' is the definition.
(king is a type of playing card)

I cannot understand how the remainder of the clue works.

(Other definitions for card that I've seen before include "Something (usually) folded with a special message" , "Stiff paper; plastic money" , "caution" , "One taken in hand" , "Posted greeting" .)

I've seen this clue in The Times.
Want a hint initially instead of a full solution? Install my app