Dr. No’s ultimate gas/talk in a boring tone (5,2)

'a boring tone' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how they can define each other.

'dr no's ultimate gastalk' is the wordplay.
'ultimate' suggests the final letters.
'gastalk' becomes 'neon' (I can't justify this - if you can you should give a lot more credence to this answer).
The last letter of 'no' is 'o'.
'dr'+'o'+'neon'='DRONE ON'

'in' acts as a link.

Can you help me to learn more?