The most common and most likely answer to this crossword clue is the 5 letter word ALKYD
I've seen this crossword clue in Independent
A
L
K
Y
D
More clues leading to the result ALKYD
Buddy explains!

The straight part
We know that "durable resin" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case durable resin = alkyd.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 ALKYD mean?
ALKYD noun- A synthetic resin derived from a reaction between alcohol and certain acids, used as a base for many laminates, paints and coatings.