The most common and most likely answer to this crossword clue is the 5 letter word DECAL
I've seen this crossword clue in The Times
D
E
C
A
L
Buddy explains!

The straight part
We know that "Design for transfer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case design for transfer = decal.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 DECAL mean?
DECAL noun- A design or picture produced in order to be transferred to another surface either permanently or temporarily.
- A decorative sticker.
- To apply decals to.