[2] He also studied at Paris, where he was admired for his oratory, and he was offered a salary of three hundred crowns if he would read a public lecture at Angers; but this he declined.
On the death of Roger Ascham he was recommended to succeed him as Latin secretary to the queen by Sir William Cecil, Robert Dudley, 1st Earl of Leicester, and Walter Haddon.
To the parliament which assembled on 2 April 1571 he was returned as one of the members for the borough of Bramber in Sussex, and on the 19th of the month he took part in a debate on the bill against usury, his speech containing quotations from Aristotle, Plato, St. Augustine, and the psalmist.
He resided with his lordship for some time after his return to England, and he was also held in esteem by Edward de Vere, 17th Earl of Oxford, to whom he was a tutor at Cambridge University.
Burghley desired some public testimony from the university respecting Clerke's conduct: the vice-chancellor and John Whitgift as Master of Trinity College, testified on 6 December 1572 to his good reputation for learning.
While engaged in refuting Sanders, Clerke was accommodated with a room in the Arches by favour of Archbishop Parker, who himself assisted in preparing the reply, which was then scrutinised and corrected by Burghley before it was sent to the press, as Fidelis servi subdito infideli responsio.
In 1587 he was again sent to the Low Countries, with his friends Lord Buckhurst and Sir John Norris, to allay the discontent which had been excited by the Earl of Leicester's proceedings in Holland, and to open the way for a peace with Spain.
His works included a translation into Latin of The Book of the Courtier from the Italian original Il Cortegiano of Baldassare Castiglione (STC 4782).
It first appeared in early 1572 as Balthasaris Castilionis Comitis De Curiali siue Aulico,[7] prefaced with commendatory Latin epistles by the Earl of Oxford, Thomas Sackville, Lord Buckhurst, and John Caius.