The most common and most likely answer to this crossword clue is the 4 letter word GROG
I've seen this crossword clue in The Times
G
R
O
G
More clues leading to the result GROG
- Almost eat too much, coming back for drink
- One of two giants swigging first of rum — a diluted type
- Stuff endlessly recycled? In brickyard, yes
- Antipodean booze binge cut back
- Getting bigger without success? This was an issue on board
- Drink 80 per cent of stuff served up
- Liquor — almost overindulge when upset
Buddy explains!

The straight part
We know that "rum — a diluted type" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rum — a diluted type = grog.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 GROG mean?
GROG noun- (original meaning) An alcoholic beverage made with rum and water, especially that once issued to sailors of the Royal Navy.
- (by extension) Any alcoholic beverage.
- A glass or serving of an alcoholic beverage.
- An alcoholic beverage made with hot water or tea, sugar and rum, sometimes also with lemon or lime juice and spices, particularly cinnamon.
- A type of pre-fired clay that has been ground and screened to a specific particle size.