Big smoker had to return around noon (4)
I believe the answer is:
etna
'big smoker' is the definition.
'etna' can be an answer for 'smoker' (volcano Mount Etna, something which 'smokes'). I am not sure about the 'big' bit.
'had to return around noon' is the wordplay.
'had' becomes 'ate' ('have' can mean 'eat').
'to return' says the letters should be written backwards.
'around' means one lot of letters goes inside another.
'noon' becomes 'n' (abbreviation).
'ate' reversed gives 'eta'.
'eta' placed around 'n' is 'ETNA'.
Can you help me to learn more?
(Other definitions for etna that I've seen before include "one blowing top?" , "Highest peak in Italy south of the Alps" , "Mount . . . . is a volcano in Sicily" , "Sicilian volcano" , "Neat volcano overturned" .)