Genius can somehow be endless (9)
I believe the answer is:
unceasing
'endless' is the definition.
(I've seen this in another clue)
'genius can somehow' is the wordplay.
'somehow' indicates an anagram.
'genius'+'can'='geniuscan'
'geniuscan' with letters rearranged gives 'UNCEASING'.
'be' is the link.
(Other definitions for unceasing that I've seen before include "Continuous" , "Not stopping" , "Endless" , "Never-ending" , "Never ending" .)