The most common and most likely answer to this crossword clue is the 9 letter word HALF-INCH
I've seen this crossword clue in The Guardian
H
A
L
F
-
I
N
C
H
Buddy explains!
The straight part
We know that "Measure appropriate for Cockneys/Measure/appropriate for Cockneys" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case measure appropriate for cockneys/measure/appropriate for cockneys = half-inch.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 HALF-INCH mean?
HALF-INCH verb- To pinch, to steal.