The most common and most likely answer to this crossword clue is the 5 letter word LOYAL
L
O
Y
A
L
More clues leading to the result LOYAL
- Firm associated with top family given new leader
- Dedicated prince possibly changing sides at the outset
- Constant contributor to employ alumni
- Behold non-clergy turning faithful
- Constant yen for a drop of Cointreau in pub
- See American university with no room for English? True!
- Large old university, not English? True
- Staunch palace resident swaps sides
- Line of Kings not initially describing how they want their subjects to be?
- … faithful left king, maybe, dropping leader
Buddy explains!

The straight part
We know that "Firm" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case firm = loyal.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 LOYAL mean?
LOYAL adjective- Having or demonstrating undivided and constant support for someone or something.
- Firm in allegiance to a person or institution.
- Faithful to a person or cause.