Give new energy to record-breaking oarsman (7)

I believe the answer is:

repower

'give new energy to' is the definition.

'record-breaking oarsman' is the wordplay.
'record' becomes 'ep'.
'breaking' means one lot of letters goes inside another.
'oarsman' becomes 'rower' ('rower' can be a synonym of 'oarsman').
'ep' placed into 'rower' is 'REPOWER'.

I've seen this clue in The Independent.

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.