Some boredom a hazard in US city (5)
I believe the answer is:
omaha
'us city' is the definition.
(I've seen this before)
'some boredom a hazard' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'OMAHA' can be found hidden inside 'boredom a hazard'.
'in' is the link.
(Other definitions for omaha that I've seen before include "This was old Indian territory" , "American Indian" , "O, a ham found in US city on Missouri river" , "American-Indians" , "American town" .)