The most common and most likely answer to this crossword clue is the 5 letter word ODDER
I've seen this crossword clue in The Daily Telegraph
O
D
D
E
R
More clues leading to the result ODDER
- Stranger died in north European river
- More unusual female ducks feed on farm
- Stranger
- Stranger not even seen by monarch
- Stranger died in European river
- More rum and food, losing head
- Stranger given food heading off
- Stranger from Communist Party turned up
- Stranger backs socialist party
- Artful dodger making grand exit with stranger
Buddy explains!

The straight part
We know that "More rum" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case more rum = odder.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 ODDER mean?
ODDER adjective- Differing from what is usual, ordinary or expected.
- Without a corresponding mate in a pair or set; unmatched; (of a pair or set) mismatched.
- Left over, remaining after the rest have been paired or grouped.
- Left over or remaining (as a small amount) after counting, payment, etc.
- Scattered; occasional, infrequent; not forming part of a set or pattern.
- Not regular or planned.
- Used or employed for odd jobs.
- Numerically indivisible by two.
- Numbered with an odd number.
- (in combination with a number) About, approximately; somewhat more than (an approximated round number).
- Out of the way, secluded.
- On the left.
- Singular in excellence; matchless; peerless; outstanding.