Individual absorbing most of powerful viral threat? (8)

'viral threat?' is the definition.

'individual absorbing most of powerful' is the wordplay.
'individual' becomes 'one'.
'absorbing' means one lot of letters goes inside another.
'most of' means to remove the last letter.
'powerful' becomes 'cogent' (I've seen this before).
'cogent' with its final letter removed is 'cogen'.
'one' placed around 'cogen' is 'ONCOGENE'.