Twit's edging in near explosive gas (6)
I believe the answer is:
natter
'gas' is the definition.
(thesaurus)
'twit's edging in near explosive' is the wordplay.
'edging' says to hollow out the word (remove centre letters) (edging means the letters on the edges).
'in' is an insertion indicator.
'explosive' is an anagram indicator.
'twit' with its middle taken out is 'tt'.
'near' anagrammed gives 'naer'.
'tt' put inside 'naer' is 'NATTER'.
(Other definitions for natter that I've seen before include "Chat - gossip" , "Gossip, maybe annoyingly" , "idle talk" , "Chew the fat, shoot the breeze" , "Talk idly" .)