The most common and most likely answer to this crossword clue is the 6 letter word FINITE
I've seen this crossword clue in The Daily Telegraph
F
I
N
I
T
E
More clues leading to the result FINITE
- Piece of fish, I note, not unlimited
- Limited punishment for stealing fortified wine
- Limited by metal casing in computers etc
- Excellent to include it, within limits
- Limited in size, it fills well
- Restricted eastern vessel if coming west
- Clear about the answer – within limits
- Utterly pleasant evening coming to an end
- Fixed penalty for smuggling in drink
- Limited it in damages
Buddy explains!

The straight part
We know that "Restricted" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case restricted = finite.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 FINITE mean?
FINITE adjective- Having an end or limit; (of a quantity) constrained by bounds; (of a set) whose number of elements is a natural number.
- (grammar, as opposed to infinite or nonfinite) limited by person or number.