Simple challenge to order from customs officer (4,3,4,4)
I believe the answer is:
open and shut case
'challenge to order from customs officer' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'simple' is the wordplay.
I cannot really understand how this works, but
'simple' could be 'openandshut' (I've seen this before) and 'openandshut' is located in the answer.
The remaining letters 'case' 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?
(Other definitions for open and shut case that I've seen before include "Straightforward procedure for detective" , "court hearing without much drama?" , "all one wants from a Customs official?" , "No problem for Holmes" , "Pack in no time at all" .)