ETYMOLOGY
from apt (intelligent, quick-witted) + -cock – a well-known suffix in surnames, as Alcock, Badcock;
probably from the use of ‘cock’ as a familiar term of appreciation for a man who fights with pluck and spirit
EXAMPLE
“…Tom marched away to school earlier than usual that afternoon, while the women went to the door and watched him trudge off, both mightily proud of his performance and his battered brown face.
“He be a reg’lar li’l apty-cock, sure ‘nough!” said Joan.
Mrs. Tregenza answered with a nod, and looked along the road after her son. …”
From: Collection of British Authors
Vol, 3228, 1897
Lying Prophets, By Eden Phillpotts
Lexicophilia 