Yes, cranes fly - it's inevitable (9)
I believe the answer is:
necessary
'inevitable' is the definition.
(similar in meaning)
'yes cranes fly' is the wordplay.
'fly' indicates anagramming the letters.
'yes'+'cranes'='yescranes'
'yescranes' is an anagram of 'NECESSARY'.
'it's' is the link.
(Other definitions for necessary that I've seen before include "Vital" , "obligatory" , "Essential, as scenery may be" , "Requisite" , "Essential, needed" .)