The most common and most likely answer to this crossword clue is the 3 letter word WET
I've seen this crossword clue in The Daily Telegraph
W
E
T
Buddy explains!
The straight part
We know that "to treat like a small child" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to treat like a small child = wet.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 WET mean?
WET noun- Liquid or moisture.
- Rainy weather.
- Rainy season. (often capitalized)
- (UK politics) A moderate Conservative; especially, one who opposed the hard-line policies of British Prime Minister Margaret Thatcher in the 1980s.
- An alcoholic drink.
- One who supports the consumption of alcohol and thus opposes Prohibition.
- (in the plural) A tyre for use in wet weather.
- To cover or impregnate with liquid.
- To accidentally urinate in or on.
- To make or become wet.
- (soldering) To form an intermetallic bond between a solder and a metal substrate.
- To celebrate by drinking alcohol.
- To kill or seriously injure.
- Made up of liquid or moisture, usually (but not always) water.
- Of an object, etc.: covered or impregnated with liquid, usually (but not always) water.
- Of a burrito, sandwich, or other food: covered in a sauce.
- Of calligraphy and fountain pens: depositing a large amount of ink from the nib or the feed.
- Of a sound recording: having had audio effects applied.
- Of weather or a time period: rainy.
- Of a person: inexperienced in a profession or task; having the characteristics of a rookie.
- (of women) Sexually aroused and thus having the vulva moistened with vaginal secretions.
- Ineffectual, feeble, showing no strength of character.
- (retronym) Permitting alcoholic beverages.
- Refreshed with liquor; drunk.
- Of a scientist or laboratory: working with biological or chemical matter.
- Employing, or done by means of, water or some other liquid.
- Involving assassination or "wet work".