Arrives at the Khyber, as happens (5,2,4)
I believe the answer is:
comes to pass
'happens' is the definition.
('come to pass' can be a synonym of 'happen')
'arrives at the khyber as' is the wordplay.
I cannot quite understand how this works, but
'arrives' could be 'comes' (coming is a kind of arriving) and 'comes' is located in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'as' is present in the answer.
The remaining letters 'ops' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for comes to pass that I've seen is " Happens".)