Group that's lost head for Scotland Yard (4)
I believe the answer is:
quad
'yard' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for quad that I've seen before include "yard" , "One of four - leg muscle" , "One of four offspring at the same birth (abbr)" , "Thigh muscle; walled space" , "bike: > one of four" .)