The most common and most likely answer to this crossword clue is the 8 letter word THIEVING
I've seen this crossword clue in Financial Times
T
H
I
E
V
I
N
G
More clues leading to the result THIEVING
Buddy explains!

The straight part
We know that "Light-fingered" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case light-fingered = thieving.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 THIEVING mean?
THIEVING verb- To commit theft.
- The action of theft.
- That thieves; that steals; inclined to steal