Go away when you shut up the holes (4)

I believe the answer is:

shoo

I'm a little stuck... Click here to teach me more about this clue!

'go away' is the definition.
(I've seen this before)

'shut up the holes' is the wordplay.
'shut up' becomes 'sh'.
'the holes' becomes 'OO' (two O's - O looks like a hole).
'sh'+'oo'='SHOO'

'when you' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for shoo that I've seen before include "Shove off!" , "Get lost!" , "Get away" , "Drive away" , "Dismissive remark" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.