The most common and most likely answer to this crossword clue is the 7 letter word OPTIMAL
O
P
T
I
M
A
L
More clues leading to the result OPTIMAL
- Most suitable gem for tiny fellow to wear
- Best man's embraced by old friend
- Best man hugged by old friend
- Flawless atrium evenly coated with gemstone
- Best, essentially, for chief with time for Republian
- Choose mail programme that’s just right
- The best work by male couple
- Best part of visual increased tenfold
- Velia’s into recreating Plato’s ideal
- Best possible period not quite set in stone
Buddy explains!

The straight part
We know that "top" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case top = optimal.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 OPTIMAL mean?
OPTIMAL noun- The best of its kind
- The best, most favourable or desirable, especially under some restriction.
- Describing a search algorithm that always returns the best result.