The most common and most likely answer to this crossword clue is the 12 letter word INTIMIDATING
I've seen this crossword clue in The Times
I
N
T
I
M
I
D
A
T
I
N
G
Buddy explains!
The straight part
We know that "Tending to cow" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tending to cow = intimidating.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 INTIMIDATING mean?
INTIMIDATING verb- To make timid or afraid; to cause to feel fear or nervousness; to deter, especially by threats of violence
- Threatening