National symbol incorporating hearts and spades separately in heading (7)
I believe the answer is:
thistle
'national symbol' is the definition.
(symbol of Scotland)
'incorporating hearts and spades separately in heading' is the wordplay.
I cannot quite understand how this works, but
'hearts' could be 'h' (abbreviation used in card games e.g. bridge) and 'h' is present in the answer.
'spades' could be 's' (abbreviation in card games) and 's' is found within the answer.
'heading' could be 'title' (title is a kind of heading) and 'title' is present in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for thistle that I've seen before include "National emblem of Scotland" , "Plant with prickly-edged leaves" , "Scottish national emblem" , "Lithest kind of prickly plant" , "Lithest (anag) - plant" .)