Humble origin of crane fly (7)
I believe the answer is:
chasten
'humble' is the definition.
(I've seen this before)
'origin of crane fly' is the wordplay.
'origin of' suggests taking the first letters.
'fly' becomes 'hasten'.
The first letter of 'crane' is 'c'.
'c'+'hasten'='CHASTEN'
(Other definitions for chasten that I've seen before include "Humble" , "Moderate" , "Punish, purify" , "Castigate or punish" , "Subdue pride of with a stench" .)