Mark is not quite on time getting into ground (11)

'mark' is the definition.
(as in a punctuation mark)

'not quite on time getting into ground' is the wordplay.
'not quite' means to remove the last letter.
'on time' becomes 'punctual' (similar in meaning).
'getting' says to put letters next to each other.
'ground' indicates an anagram ('grind' the letters into a new form).
'punctual' with its last letter removed is 'punctua'.
'into' with letters rearranged gives 'tion'.
'punctua'+'tion'='PUNCTUATION'

'is' is the link.