Rugby Union girl gets German measles (7)
I believe the answer is:
rubella
'german measles' is the definition.
(synonyms)
'rugby union girl' is the wordplay.
'rugby union' becomes 'RU' (abbreviation).
'girl' becomes 'bella' ().
'ru'+'bella'='RUBELLA'
'gets' is the link.
(Other definitions for rubella that I've seen before include "infection" , "German measles" , "complaint" , "contagious disease" .)