The most common and most likely answer to this crossword clue is the 6 letter word LITTER
I've seen this crossword clue in The Sunday Telegraph
L
I
T
T
E
R
Buddy explains!
The straight part
We know that "Babies/make a mess" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case babies/make a mess = litter.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 LITTER mean?
LITTER noun- A platform mounted on two shafts, or a more elaborate construction, designed to be carried by two (or more) people to transport one (in luxury models sometimes more) third person(s) or (occasionally in the elaborate version) a cargo, such as a religious idol.
- (collective) The offspring of a mammal born in one birth.
- Material used as bedding for animals.
- Collectively, items discarded on the ground.
- Absorbent material used in an animal's litter tray
- Layer of fallen leaves and similar organic matter in a forest floor.
- A covering of straw for plants.
- To drop or throw trash without properly disposing of it (as discarding in public areas rather than trash receptacles).
- To scatter carelessly about.
- To strew (a place) with scattered articles.
- To give birth to, used of animals.
- To produce a litter of young.
- To supply (cattle etc.) with litter; to cover with litter, as the floor of a stall.
- To be supplied with litter as bedding; to sleep or make one's bed in litter.