Greek letter from English essayist to American lawman (6)
I believe the answer is:
'greek letter' is the definition.
(letter from the Greek alphabet)
'english essayist to american lawman' is the wordplay.
'english essayist' becomes 'lamb' (I've seen this before).
'to' is a charade indicator (letters next to each other).
'american lawman' becomes 'da' (I am not sure about the 'american' bit.).
'from' acts as a link.
Can you help me to learn more?
(Other definitions for lambda that I've seen before include "Teasing entertainer" , "Greek letter - am bald (anag)" , "Not one of our characters" , "The 11th letter of the Greek alphabet" , "Foreign character" .)