The most common and most likely answer to this crossword clue is the 3 letter word TUP
I've seen this crossword clue in The Daily Telegraph
T
U
P
More clues leading to the result TUP
Buddy explains!

The straight part
We know that "ram" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ram = tup.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 TUP mean?
TUP noun- A male sheep, a ram.
- The head of a hammer, and particularly of a steam-driven hammer.
- To mate; used of a ram mating with a ewe.
- To have sex with, to bonk, etc.
- (regional English) To butt: said of a ram.
- Two pence.