The most common and most likely answer to this crossword clue is the 5 letter word HOPED
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More clues leading to the result HOPED
Buddy explains!

The straight part
We know that "Kept the faith" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case kept the faith = hoped.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 HOPED mean?
HOPED verb- To want something to happen, with a sense of expectation that it might.
- To be optimistic; be full of hope; have hopes.
- To place confidence; to trust with confident expectation of good; usually followed by in.
- To wish.