Clerk, who came from Ollerton, is first noticed in September 1399, when he witnessed a deed at Leicester. Shortly afterwards, he became feodary for the Crown of estates in the Midlands forfeited by those executed for their part in the abortive rebellion on behalf of the recently deposed Richard II. It was just a few months after he represented Leicester in the Parliament of 1401, that he was elected mayor. Thereafter, from 1402 until 1409, he was more or less continuously involved in administering duchy of Lancaster estates in the region. It was probably his position as, successively, receiver and feodary that gained him his place on a commission of array of 1403 and on another set up to inquire into the ownership of Hallaton in 1408. By 1407, in which year he stood surety for the parliamentary attendance of John Blaket, knight of the shire for Leicestershire, he was receiving a duchy annuity of 40s. a year from the issues of Leicester honour, and in the following year this sum was increased to £5.4Wyggeston Hosp. Recs. ed. Thompson, no. 568; C219/10/4; DL28/27/9; DL42/16, f. 235.
Clerk held land at Slawston and Othorpe, Leicestershire. He is not known to have owned any property in Leicester itself, though he was a benefactor of the Newarke college and hospital there, which were duchy of Lancaster foundations. He was dead by 1418.5CPR, 1391-6, p. 13; 1396-9, p. 443; CP25(1)126/73, 22, 24.