The Italian will disrupt flying, regular and irregular (9)
I believe the answer is:
guerrilla
'irregular' is the definition.
(I know that irregular can be written as guerrilla)
'the italian will disrupt flying regular' is the wordplay.
'the italian' becomes 'il' (Italian for 'the').
'will disrupt' means one lot of letters goes inside another (inside letters 'disrupt' the flow of outside one).
'flying' indicates an anagram (letters fly around into new positions).
'regular' with letters rearranged gives 'guerrla'.
'il' put within 'guerrla' is 'GUERRILLA'.
'and' is the link.
(Other definitions for guerrilla that I've seen before include "political insurgent" , "Irregular fighter" , "Irregular bandit" , "Politically motivated fighter" , "Irregular soldier" .)