The most common and most likely answer to this crossword clue is the 7 plus 7 letter word HEALTHY RESPECT
I've seen this crossword clue in The Guardian
H
E
A
L
T
H
Y
R
E
S
P
E
C
T
Buddy explains!
The straight part
We know that "Esteem shown for those that are fit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case esteem shown for those that are fit = healthy respect.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.