Is monocle ruined? There's a little mark (9)
I believe the answer is:
semicolon
'a little mark' is the definition.
'is monocle ruined?' is the wordplay.
'ruined?' is an anagram indicator.
'is'+'monocle'='ismonocle'
'ismonocle' with letters rearranged gives 'SEMICOLON'.
'there's' is the link.
(Other definitions for semicolon that I've seen before include "can cut sentence" , "Item of punctuation" , "half a stop" , "Joiner" , "Punctuation mark denoting a pause in a sentence" .)