Press for admission to surgery (4)

I believe the answer is:

urge

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

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

'admission to surgery' is the wordplay.
'URGE' is hidden within the letters.
However, I am unsure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for urge that I've seen before include "Strongly encourage" , "Appeal to" , "'Exhort, press (4)'" , "Impel, exhort" , "Egg on, encourage to proceed" .)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app