2 centres (6)
I believe the answer is:
hearts
This could be a double definition.
'2' is the first definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'centres' is the second definition.
(I know this)
Can you help me to learn more?
(Other definitions for hearts that I've seen before include "Playing-card suit" , "Red suit" , "Card game and centres of emotions, it's said" , "Soccer club" , "Scots club nickname; suit" .)