The most common and most likely answer to this crossword clue is the 8 letter word REASSESS
I've seen this crossword clue in The Guardian
R
E
A
S
S
E
S
S
More clues leading to the result REASSESS
- Take another look at donkeys put in reserve
- Have second thoughts about bums on seats finally
- Fools, amongst others, curtailed check again
- Review concerning animal on European ship
- Have another look at animals kept in reserve briefly
- Think twice about seas breaking over ship
- Think again about Welshman lagging behind on bend
- About to start, seas break over ship — so reconsider
- Think again about people who are foolish
- Break, when case leader goes for idiot judge again
Buddy explains!

The straight part
We know that "Think twice" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case think twice = reassess.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 REASSESS mean?
REASSESS verb- To assess again; to revise an earlier assessment; to reevaluate