Showing impertinence precludes fist flying (13)
I believe the answer is:
disrespectful
'showing impertinence' is the definition.
'precludes fist flying' is the wordplay.
'flying' indicates anagramming the letters.
'precludes'+'fist'='precludesfist'
'precludesfist' is an anagram of 'DISRESPECTFUL'.
(Other definitions for disrespectful that I've seen before include "Impolite" , "Uncivil" , "Rude" , "Impudent" , "Insulting" .)