Week One in US series is sentimental (7)

I believe the answer is:

mawkish

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

'is sentimental' is the definition.
(synonyms)

'week one in us series' is the wordplay.
'week' becomes 'wk' (common abbreviation).
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'us series' becomes 'mash' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'wk'+'i'='wki'
'wki' inserted into 'mash' is 'MAWKISH'.

Can you help me to learn more?

(Other definitions for mawkish that I've seen before include "Effusively or insincerely emotional" , "Sentimental in maudlin way" , "Insipid; maudlin" , "Cloying" , "Falsely sentimental" .)

I've seen this clue in The Guardian.

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.