The most common and most likely answer to this crossword clue is the 5 letter word OVINE
I've seen this crossword clue in The Times
O
V
I
N
E
More clues leading to the result OVINE
- Like sheep, cow loses its head
- One creeping on round, sheepish?
- Like lamb I placed in oven, well-cooked
- Possibly sheepish old climber
- Old climber like Jacob?
- Like sheep or like cow
- Naked lover staying at home is sheepish?
- . Sheepish individual seen around six
- Grapes not available then? Fleeced?
- Sheepish old climber
Buddy explains!

The straight part
We know that "like Jacob?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case like jacob? = ovine.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 OVINE mean?
OVINE noun- A sheep.
- Of, pertaining to, resembling, or being a sheep
- (by extension) resembling a sheep in character; passive, of low intelligence and acquiescent