Gas trouble among our sailors (5)
I believe the answer is:
radon
'gas' is the definition.
(I know that radon is a type of argonon)
'trouble among our sailors' is the wordplay.
'trouble' becomes 'ado' (both can mean bother or commotion).
'among' is an insertion indicator.
'our sailors' becomes 'RN' (Royal Navy).
'ado' placed within 'rn' is 'RADON'.
(Other definitions for radon that I've seen before include "Element, symbol Rn" , "hazardous substance" , "Gaseous element, Rn" , "Rare noble gas" , "Naturally occurring inert gas" .)