Beat a Tibetan monk (4)
I believe the answer is:
lama
'tibetan monk' is the definition.
(I've seen this before)
'beat a' is the wordplay.
'beat' becomes 'lam' (I've seen this before**).
'lam'+'a'='LAMA'
(Other definitions for lama that I've seen before include "Dalai . . . ., chief priest and once ruler of Tibet" , "Tibetan high priest" , "Holy man in Tibet" , "A Tibetan Buddhist priest or monk" , "A Buddhist priest in Tibet (4)" .)