Rattle is interrupting when making showy greeting (3,4)
I believe the answer is:
air kiss
'showy greeting' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'rattle is interrupting when' is the wordplay.
'rattle' becomes 'irk' (I can't justify this - if you can you should believe this answer much more).
'interrupting' is an insertion indicator.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'irk'+'is'='irkis'
'irkis' placed within 'as' is 'AIR-KISS'.
'making' is the link.
Can you help me to learn more?
(Other definitions for air kiss that I've seen before include "contactless transaction" , "form of greeting" , "Greeting that's not touching" .)