Thirteen cards for eleven players in Scotland? (6)
I believe the answer is:
hearts
'thirteen cards' is the definition.
'hearts' can be an answer for 'cards' (heart is a kind of card). I'm not sure about the 'thirteen' bit.
I cannot understand how the rest of the clue works.
(Other definitions for hearts that I've seen before include "Cores" , "Scottish footballers" , "Red playing cards" , "Playing-card suit" , "Suit in pack" .)