Customs men may look here, whatever happens (2,3,4)
I believe the answer is:
in any case
'whatever happens' is the definition.
(I've seen this before)
'customs men may look here' is the wordplay.
I cannot really understand how this works, but
'men' could be 'se' (I have seen 'Spanish men ' mean 'se' so perhaps 'men' could also mean 'se') and 'se' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for in any case that I've seen before include "Lawyers may be so employed" , "Where a customs officer may search" , "No matter what" , "Whatever the facts are, whatever happens" , "At all events" .)