Call large bird, not difficult in East London (4)
I believe the answer is:
buzz
'call' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for buzz that I've seen before include "Stimulation - sound of bee" , "phone call" , "Sense of excitement" , "Bee's noise" , "do like insects when flying" .)