The most common and most likely answer to this crossword clue is the 5 letter word CLEFT
I've seen this crossword clue in The Guardian
C
L
E
F
T
More clues leading to the result CLEFT
- Socialists pursuing Conservative split
- Conservative opponents of right in split
- Divided with a hundred over.
- Split, one hundred remaining
- Conservative taking port and crack
- Conservative/Labour split
- Split from leader of Champagne socialists
- Rift between Conservative and Labour?
- Conservative and socialist split
- Croatia’s foremost port is Split
Buddy explains!

The straight part
We know that "Rift" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rift = cleft.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 CLEFT mean?
CLEFT noun- An opening, fissure, or V-shaped indentation made by or as if by splitting.
- A piece made by splitting.
- A disease of horses; a crack on the band of the pastern.
- To syntactically separate a prominent constituent from the rest of the clause that concerns it, such as threat in "The threat which I saw but which he didn't see, was his downfall."
- To split or sever something with, or as if with, a sharp instrument.
- To break a single crystal (such as a gemstone or semiconductor wafer) along one of its more symmetrical crystallographic planes (often by impact), forming facets on the resulting pieces.
- To make or accomplish by or as if by cutting.
- To split (a complex molecule) into simpler molecules.
- To split.
- Of a crystal, to split along a natural plane of division.
- Split, divided, or partially divided into two.