Keep an eye on certain short curtain (7)

I believe the answer is:

surveil

'keep an eye on' is the definition.
(I've seen this in another clue)

'certain short curtain' is the wordplay.
'certain' becomes 'sure' (synonyms).
'short' means to remove the last letter.
'curtain' becomes 'veil' (I've seen this before).
'sure' with its last letter taken away is 'sur'.
'sur'+'veil'='SURVEIL'

(Another definition for surveil that I've seen is " Monitor".)

I've seen this clue in The Guardian.

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