Check on luggage may create a precedent (4,4)
I believe the answer is:
test case
'a precedent' is the definition.
(I've seen this before)
'check on luggage' is the wordplay.
'check' becomes 'test' (as in testing or checking something works).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'luggage' becomes 'case' (eg a suitcase).
'test'+'case'='TEST-CASE'
'may create' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for test case that I've seen before include "that could set a precedent" , "Legal action serving as a precedent" , "Lawsuit seeking decision asprecedent" , "One may set a precedent" , "Forensic proof" .)