The most common and most likely answer to this crossword clue is the 4 letter word EGAD
I've seen this crossword clue in The Times
E
G
A
D
More clues leading to the result EGAD
- The old curse for example ahead of active duty
- Say a heartily dodgy oath
- Last one of the tribe to give utterance of surprise
- My word once accepted by renegade
- Mature, upwardly mobile daughter, dated brother
- England regularly failing, dammit
- Christ appearing in England, oddly
- My word for one accompanying a duke
- Days and years on earth rising? Blimey!
- Odds on England, odds bodkins!
Buddy explains!

The straight part
We know that "dated brother" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dated brother = egad.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 EGAD mean?
EGAD interjection- A mild exclamation of surprise, contempt, outrage, etc.