Prove vat ideal for cooking (8)
I believe the answer is:
validate
'prove' is the definition.
(I've seen this before)
'vat ideal for cooking' is the wordplay.
'for cooking' indicates an anagram.
'vat'+'ideal'='vatideal'
'vatideal' with letters rearranged gives 'VALIDATE'.
(Other definitions for validate that I've seen before include "stand by" , "Confirm truth of (item)" , "Prove" , "Corroborate" , "Confirm as true" .)