Happen as a result of largely unseen wavering (5)
I believe the answer is:
ensue
'happen as a result' is the definition.
(I've seen this before)
'largely unseen wavering' is the wordplay.
'largely' means to remove the last letter.
'wavering' indicates anagramming the letters.
'unseen' with its last letter taken off is 'unsee'.
'unsee' with letters rearranged gives 'ENSUE'.
'of' acts as a link.
(Other definitions for ensue that I've seen before include "Follow as a consequence" , "Arise" , "Happen as consequence or afterward" , "Cultivate plants/vegetables" , "Come about, result in" .)