The most common and most likely answer to this crossword clue is the 5 letter word RENEW
I've seen this crossword clue in The Guardian
R
E
N
E
W
More clues leading to the result RENEW
- Sausage returned after one’s dropped — start again
- Frenchman needing whiskey to get going again
- Replace Descartes, perhaps, with Watt
- Low energy holds back what regeneration will do
- Central area owners vowed to make fresh again
- Renovate Magritte, perhaps, with tip of hacksaw
- Give refreshment to Frenchman and wife
- Continue with German sausage roll? Not I
- Frenchman’s wife to start again
- Little women, never disheartened, about to begin again
Buddy explains!

The straight part
We know that "to start again" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to start again = renew.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RENEW mean?
RENEW verb- To make (something) new again; to restore to freshness or original condition.
- To replace (something which has broken etc.); to replenish (something which has been exhausted), to keep up a required supply of.
- To make new spiritually; to regenerate.
- To become new, or as new; to revive.
- To begin again; to recommence.
- To repeat.
- To extend a period of loan, especially a library book that is due to be returned.
- The act of renewing.
- An offensive action made immediately after a parried one.