Finish work immediately, you understand (4)
I believe the answer is:
know
'understand' is the definition.
(I've seen this before)
'finish work immediately' is the wordplay.
'finish' indicates one should take the final letters.
'immediately' becomes 'now' (I've seen this before).
The final letter of 'work' is 'k'.
'k'+'now'='KNOW'
'you' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for know that I've seen before include "Articulated" , "Recognise" , "Understand" , "Be acquainted with" , "Be familiar with" .)