Two gangsters filling airline sickbag regularly - it's stringy? (9)

I believe the answer is:

balalaika

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'it's stringy?' is the definition.
I can't judge whether this definition defines the answer.

'two gangsters filling airline sickbag regularly' is the wordplay.
'two gangsters' means two substitutions for 'gangster'.
'gangster' becomes 'al' (Al Capone).
'gangster' becomes 'al' (Al Capone).
'filling' is an insertion indicator.
'airline' becomes 'BA' (British Airways).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'sickbag' are 'ika'.
'al'+'al'='alal'
'alal' inserted into 'ba' is 'balala'.
'balala'+'ika'='BALALAIKA'

Can you help me to learn more?

(Other definitions for balalaika that I've seen before include "Russian "guitar"" , "Foreign instrument" , "Instrument with three strings and a triangular body" , "Russian guitar-like instrument" , "Three-stringed, triangularbodied Russian instrument" .)

I've seen this clue in The Independent.

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