It's concerning to see a rugby player having lost heart (7)
I believe the answer is:
apropos
'it's concerning' is the definition.
(apropos means referring to or concerning a topic)
'a rugby player having lost heart' is the wordplay.
'rugby player' becomes 'prop' (type of rugby player).
'having' says to put letters next to each other.
'heart' indicates the central letters.
The centre of 'lost' is 'os'.
'a'+'prop'+'os'='APROPOS'
'to see' is the link.
(Other definitions for apropos that I've seen before include "Poor sap (anag) - to the purpose" , "Suitable or relevant" , "well-chosen" , "With regard to" , "On the subject of" .)