Empty talk by swell high-flier? (3-3,7)
I believe the answer is:
hot-air balloon
'high-flier?' is the definition.
(a hot-air balloon goes up into the sky)
'empty talk by swell' is the wordplay.
'empty talk' becomes 'hot air' (synonyms).
'by' means one lot of letters go next to another.
'swell' becomes 'balloon' (both can mean to expand or increase).
'hotair'+'balloon'='HOT-AIR BALLOON'
(Other definitions for hot-air balloon that I've seen before include "Flame-powered craft" , "Aerial transport" , "Basket lifter" , "Craft using heat to gain altitude" , "Lighter-than-air craft" .)