Lions come running; this is the end (9)
I believe the answer is:
semicolon
'the end' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'lions come running' is the wordplay.
'running' is an anagram indicator.
'lions'+'come'='lionscome'
'lionscome' with letters rearranged gives 'SEMICOLON'.
'this is' is the link.
(Other definitions for semicolon that I've seen before include "used by writers for a break" , "Punctuation mark denoting a pause in a sentence" , "can cut sentence" , "half a stop" , "Joiner" .)