Sporting official swore over nothing and concentrated again (10)

I believe the answer is:

refocussed

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

'concentrated again' is the definition.
The definition suggests a past participle verb which matches the answer.

'sporting official swore over nothing' is the wordplay.
'sporting official' becomes 'ref' (short for referee).
'swore' becomes 'cussed' ('cuss' can be a synonym of 'swear').
'over' indicates putting letters inside.
'nothing' becomes 'O' (looks like zero - 0).
'ref'+'cussed'='refcussed'
'refcussed' enclosing 'o' is 'REFOCUSSED'.

'and' is the link.

Can you help me to learn more?

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.