Seated, awfully tranquil (6)
I believe the answer is:
sedate
'tranquil' is the definition.
(I've seen this in another clue)
'seated awfully' is the wordplay.
'awfully' is an anagram indicator.
'seated' anagrammed gives 'SEDATE'.
(Other definitions for sedate that I've seen before include "Quiet and dignified" , "Placid" , "Teased into being calm" , "Staid and sober" , "Unhurried; drug" .)