Hint that single nun makes nothing after closing (8)
I believe the answer is:
innuendo
'hint' is the definition.
(I've seen this before)
'single nun makes nothing after closing' is the wordplay.
'single' becomes 'I' (one).
'makes' is an anagram indicator.
'nothing' becomes 'O' (O resembles 0).
'after' is a charade indicator (letters next to each other).
'closing' becomes 'end' (I've seen this in another clue).
'nun' anagrammed gives 'nnu'.
'o' put after 'end' is 'endo'.
'i'+'nnu'+'endo'='INNUENDO'
'that' is the link.
(Other definitions for innuendo that I've seen before include "suggestive remarks" , "derogatory reference" , "Suggestiveness" , "End union with insinuation" , "Rude suggestion" .)