Fool takes plunge short time later
I believe the answer is:
dipstick
'fool' is the definition.
(I've seen this before)
'plunge short time later' is the wordplay.
'plunge' becomes 'dip' ('dip' can be a synonym of 'plunge').
'short time later' becomes 'stick' (I can't explain this - if you can you should believe this answer much more).
'dip'+'stick'='DIPSTICK'
'takes' acts as a link.
Can you help me to learn more?
(Other definitions for dipstick that I've seen before include "Graduated rod for measuring oil levels" , "Device for checking oil level" , "plunged into engine oil?" , "Rod used to measure oil level in car" , "Engine oil measurer" .)