Seller of cooker missing ring to con rector (6)
I believe the answer is:
vendor
'seller' is the definition.
(I know that seller can be written as vendor)
'cooker missing ring to con rector' is the wordplay.
'cooker' becomes 'oven' (synonyms).
'missing' indicates named letters should be taken away.
'ring' becomes 'O' (letter resembling a ring).
'to con' becomes 'do' (to 'do' someone could be to con them).
'rector' becomes 'r'.
'oven' with 'o' taken away is 'ven'.
'ven'+'do'+'r'='VENDOR'
'of' acts as a link.
(Other definitions for vendor that I've seen before include "One flogging" , "Seller, trader (O, not E)" , "One selling house" , "who does business?" , "Person selling" .)