Where butt is awfully hot, sat by sunlight (7)
I believe the answer is:
ashtray
'where butt is' is the definition.
(where a cigarette butt goes)
'awfully hot sat by sunlight' is the wordplay.
'awfully' indicates anagramming the letters.
'hot' becomes 'h'.
'by' is a charade indicator (letters next to each other).
'sunlight' becomes 'ray' (as in a ray of sunlight).
'h'+'sat'='hsat'
'hsat' is an anagram of 'asht'.
'asht'+'ray'='ASHTRAY'
(Other definitions for ashtray that I've seen before include "Place for detritus from cigarettes, cigars etc" , "Where to rest cigarette" , "Smoker's receptacle" , "where smoking remains are found" , "Place for cigarette ends" .)