Gas poker! (6)
I believe the answer is:
jabber
I believe this clue is a double definition.
'gas' is the first definition.
(thesaurus)
'poker' is the second definition.
(I've seen this before)
(Other definitions for jabber that I've seen before include "indistinct speech" , "Rapid (foreign) talk" , "Gabble, talk rapidly" , "Talk quickly and indistinctly" , "one giving vaccination" .)