Group of witches beginning to clean stove (5)
I believe the answer is:
coven
'group of witches' is the definition.
(I've seen this before)
'beginning to clean stove' is the wordplay.
'beginning to' indicates taking the first letters.
'stove' becomes 'oven' (I've seen this before).
The first letter of 'clean' is 'c'.
'c'+'oven'='COVEN'
(Other definitions for coven that I've seen before include "collection of bewitching women" , "Charming women" , "Gathering of witches" , "Witch group" , "Some wise women" .)