Beat yak with shortened device (6)
I believe the answer is:
patter
'beat' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for patter that I've seen before include "Noise of fast light steps" , "See 1" , "Spiel" , "Salesman's persuasive talk" , "Salesperson's talk" .)