W A —, English clergyman renowned for his transposition of the initial consonants of a pair of words in a sentence (7)
I believe the answer is:
spooner
(Other definitions for spooner that I've seen before include "Revd W.A.- was famed for his errors in speech" , "One known for speech transpositions" , "Tongue-tied man" , "One who gave his name to a transposition of sounds in speech" , "Original transposer of initial letters in speech" .)