The most common and most likely answer to this crossword clue is the 11 letter word PHOTOCOPIER
I've seen this crossword clue in Financial Times
P
H
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T
O
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Buddy explains!

The straight part
We know that "image-maker" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case image-maker = photocopier.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 PHOTOCOPIER mean?
PHOTOCOPIER noun- A machine which reproduces documents by photographing the original over a glass plate and printing duplicates.