One dubious name for inert gas (4)
I believe the answer is:
neon
'inert gas' is the definition.
(I've seen this before)
'one dubious name' is the wordplay.
'dubious' indicates an anagram.
'name' becomes 'n' (common abbreviation e.g. on forms).
'one' with letters rearranged gives 'neo'.
'neo'+'n'='NEON'
'for' is the link.
(Other definitions for neon that I've seen before include "'Chemical element, often used in lights (4)'" , "Element that gives a red glow in a vacuum tube" , "Inert gas, symbol Ne" , "Form of lighting" , "Gaseous element, in advertising sign say" .)