Where one might strike a hammer without delay (2,3,4)
I believe the answer is:
on the nail
'without delay' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for on the nail that I've seen before include "Where a hammer might go" , "Where varnish is put" , "Exact" , "focus of manicurist?" , "Prompt" .)