The most common and most likely answer to this crossword clue is the 5 plus 2 letter word BUILT UP
I've seen this crossword clue in The Guardian
B
U
I
L
T
U
P
More clues leading to the result BUILT UP
Buddy explains!
The straight part
We know that "where speed limit is likely" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case where speed limit is likely = built up.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 BUILT UP mean?
BUILT UP adjective- Made of sections or layers, one on top of the other.
- Having increased in size, quantity, or intensity over time; accumulated.
- Constructed or enhanced.
- (of an area of land) Having buildings, especially having residences and high population density.
- (of an area of land) Having street lights and therefore subject to a 30 mph speed limit.
- (Europe) (of an area of land) Having specific traffic signaling and therefore usually subject to a maximum 50 km/h speed limit.