A crack that can lead to much strife (4)

I believe the answer is:

rift

I'm a little stuck... Click here to teach me more about this clue!

'a crack' is the definition.
(I know that rift is a type of crack)

I can't explain the remainder of the clue.

(Other definitions for rift that I've seen before include "Break in relations; type of valley" , "A disagreement or an earth cleft" , "Cleft or fissure" , "Schism (in the lute?)" , "Breach, rupture" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app