Sleepyhead doesn't count sheep by stone wall (5)
I believe the answer is:
delay
'wall' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for delay that I've seen before include "Put off until later" , "Stoppage" , "hold-up of train?" , "Postponement" , "Time lapse" .)