US city postgraduate becoming priest (4)
I believe the answer is:
lama
'priest' is the definition.
(I know that lama is a type of priest)
'us city postgraduate' is the wordplay.
'us city' becomes 'LA' (Los Angeles).
'postgraduate' becomes 'ma' (Master of Arts is a postgraduate degree).
'la'+'ma'='LAMA'
'becoming' acts as a link.
(Other definitions for lama that I've seen before include "Tibetan spiritual leader" , "Holy man in Tibet" , "Dalai . . . ., chief priest and once ruler of Tibet" , "Religious leader" , "A Tibetan Buddhist priest or monk" .)