Lenin wasn't prepared for activity in court (4,6)
I believe the answer is:
lawn tennis
'activity in court' is the definition.
'lenin wasn't prepared' is the wordplay.
'prepared' indicates an anagram.
'lenin'+'wasnt'='leninwasnt'
'leninwasnt' anagrammed gives 'LAWN TENNIS'.
'for' is the link.
(Other definitions for lawn tennis that I've seen before include "Court game" , "sport" , "Real alternative" , "Wimbledon game" , "court action results" .)