The most common and most likely answer to this crossword clue is the 8 letter word RESOLVED
I've seen this crossword clue in The Guardian
R
E
S
O
L
V
E
D
More clues leading to the result RESOLVED
- Decided on finished puzzle
- Old verse after a rewrite worked out
- Settled lovers broken up by journalist
- Cracked clues once more, being determined
- Someone beaten up over a holy book endlessly becomes determined
- Decided to back loser against current Labour leader
- Determined to dispel doubts at the outset
- Worked out commitment on debt initially
- Determined, completed the Toughie again?
- Very determined, so worked out again
Buddy explains!

The straight part
We know that "determined" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case determined = resolved.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 RESOLVED mean?
RESOLVED verb- To find a solution to (a problem).
- To reduce to simple or intelligible notions; to make clear or certain; to unravel; to explain.
- To make a firm decision to do something.
- To determine or decide in purpose; to make ready in mind; to fix; to settle.
- To come to an agreement or make peace; patch up relationship, settle differences, bury the hatchet.
- To break down into constituent parts; to decompose; to disintegrate; to return to a simpler constitution or a primeval state.
- To cause to perceive or understand; to acquaint; to inform; to convince; to assure; to make certain.
- To cause a chord to go from dissonance to consonance.
- To render visible or distinguishable the parts of something.
- To find the IP address of a hostname, or the entity referred to by a symbol in source code; to look up.
- To melt; to dissolve; to liquefy or soften (a solid).
- To melt; to dissolve; to become liquid.
- To liquefy (a gas or vapour).
- To disperse or scatter; to discuss, as an inflammation or a tumour.
- To relax; to lay at ease.
- To separate racemic compounds into their enantiomers.
- To solve (an equation, etc.).
- To solve again.
- Determined; fixed in one's purpose