Number one confronts worker directly (9)

'directly' is the definition.
(as in something experienced firsthand or directly)

'number one confronts worker' is the wordplay.
'number one' becomes 'first' (synonyms).
'confronts' means one lot of letters go next to another (two parts meet or confront each other).
'worker' becomes 'hand' (hand is a kind of worker).
'first'+'hand'='FIRSTHAND'