The most common and most likely answer to this crossword clue is the 7 letter word MANGERS
I've seen this crossword clue in The Sunday Telegraph
M
A
N
G
E
R
S
Buddy explains!

The straight part
We know that "one of which had another role at Christmas" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one of which had another role at christmas = mangers.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 MANGERS mean?
MANGERS noun- A trough for animals to eat from.