Measures out so as to set 'em up (5)

I believe the answer is:

metes

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

'measures' is the definition.
(I've seen this in another clue)

'set 'em up' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'set'+'em'='setem'
'setem' in reverse letter order is 'METES'.

'out so as to' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Another definition for metes that I've seen is " Hands (out)".)

I've seen this clue in the Evening Standard.

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