Hearts blocking French football club's corner (5)
I believe the answer is:
niche
'corner' is the definition.
(synonyms)
'hearts blocking french football club's' is the wordplay.
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'blocking' is an insertion indicator (block can mean to plug a gap in something).
'french football club's' becomes 'nice' (I can't explain this - if you can you should believe this answer much more).
'h' put inside 'nice' is 'NICHE'.
Can you help me to learn more?
(Other definitions for niche that I've seen before include "small specialised market" , "Suitable slot" , "Comfortable position" , "Calling" , "hole" .)