The most common and most likely answer to this crossword clue is the 8 letter word FIDDLIER
I've seen this crossword clue in Financial Times
F
I
D
D
L
I
E
R
Buddy explains!

The straight part
We know that "harder to handle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case harder to handle = fiddlier.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.
Crossword Answer definitions
FIDDLIER adjective- Requiring dexterity to operate.
- (by extension) Having many small bits or embellishments.
- Of or relating to fiddling or fidgeting.
- Pertaining to occasional under-the-table work by people who receive unemployment benefits