Insignificance of man with no picture being shot (12)
I believe the answer is:
unimportance
'insignificance' is the definition.
(thesaurus)
'man with no picture being shot' is the wordplay.
'with' is a charade indicator (letters next to each other).
'being shot' indicates anagramming the letters.
'man'+'no'+'picture'='mannopicture'
'mannopicture' is an anagram of 'UNIMPORTANCE'.
'of' acts as a link.
(Other definitions for unimportance that I've seen before include "Insignificance" , "Lack of significance" .)