Genning up: it regularly leads to boredom (5)
I believe the answer is:
ennui
'boredom' is the definition.
(I know that boredom can be written as ennui)
'genning up it regularly' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'genning'+'up'+'it'='genningupit'
The alternating letters of 'genningupit' are 'ENNUI'.
'leads to' is the link.
(Other definitions for ennui that I've seen before include "Lack of interest" , "to make one list less when connected" , "depression" , "Result of boredom" , "The feeling of being bored" .)