Oven with a halo round it when working? (4)
I believe the answer is:
oast
'oven' is the definition.
(type of kiln)
'halo round it when working?' is the wordplay.
I cannot really understand how this works, but
'halo' could be 'o' (O resembles a halo) and 'o' is found within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
'when' could be 'as' (eg 'when I walked' means 'as I walked') and 'as' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'with a' is the link.
Can you help me to learn more?
(Other definitions for oast that I've seen before include "Hop-drying kiln" , "Drying house" , "Kiln for drying hops or malt" , "Hop-kiln" , "Oven for hops" .)