Wash and scrub the clams and put in a large saucepan.
Cover pan with lid and place over a high heat for 3-4 minutes. Give this a shake every minute, until all the clams have opened and discard any that remain closed.
Strain into a sieve and reserve the clam juice.
In a separate pan, heat oil and add the garlic until lightly coloured.
Stir in the anchovy paste/fillets and then add the tomatoes along with the reserved clam juice and wine.
Add the parsley and bring to the boil, then simmer, uncovered for 20 minutes.
Add seasoning to taste and toss in the spaghetti until well coated with the clam mixture.