Boil tuna after mincing and washing (8)
I believe the answer is:
ablution
'washing' is the definition.
(ablution is a kind of washing)
'boil tuna after mincing' is the wordplay.
'boil tuna' can be anagrammed to 'ABLUTION'.
But, I am not sure how this is indicated.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for ablution that I've seen before include "Toilet facility" , "Ceremonial washing of hands" , "Ritual washing in church" , "About nil (anag.)" , "Washing process" .)