Close to Bethlehem, a relic exciting wonder (7)
I believe the answer is:
miracle
'wonder' is the definition.
(I've seen this in another clue)
'close to bethlehem a relic exciting' is the wordplay.
'close to' indicates one should take the final letters (the close/ending of).
'exciting' is an anagram indicator.
The final letter of 'bethlehem' is 'm'.
'a'+'relic'='arelic'
'arelic' is an anagram of 'iracle'.
'm'+'iracle'='MIRACLE'
(Other definitions for miracle that I've seen before include "Unexplained wonder" , "astonishing feat" , "Divine action" , "Amazing event" , "Divinely-inspired event" .)