Focal length embedded? (4)
I believe the answer is:
colt
'focal length' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for colt that I've seen before include "Type of revolver and a young horse" , "Young male horse or cowboy revolver" , "firearm" , "Mount" , "shooter" .)