Garrulous, like a TV lunatic absorbing atmosphere (9)
I believe the answer is:
talkative
'garrulous' is the definition.
('talkative' can be a synonym of 'garrulous')
'like a tv lunatic absorbing atmosphere' is the wordplay.
'lunatic' is an anagram indicator.
'absorbing' means one lot of letters goes inside another.
'atmosphere' becomes 'at' (abbreviation).
'like'+'a'+'tv'='likeatv'
'likeatv' anagrammed gives 'talkive'.
'talkive' placed around 'at' is 'TALKATIVE'.
(Other definitions for talkative that I've seen before include "Voluble" , "Wordy" , "Gabby" , "Garrulous, loquacious" , "of many words" .)