Honour resistance blocking onset of climate change (6)
I believe the answer is:
credit
'honour' is the definition.
(I've seen this before)
'resistance blocking onset of climate change' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'blocking' indicates putting letters inside (to block can mean to plug a gap in something).
'onset of' suggests taking the first letters.
'change' becomes 'edit' (edit can mean to change or alter).
The first letter of 'climate' is 'c'.
'c'+'edit'='cedit'
'r' placed into 'cedit' is 'CREDIT'.
(Other definitions for credit that I've seen before include "Acknowledgment, recognition or praise" , "Believe - one side of an account" , "support for one with money problems" , "Tick - distinction" , "good grade" .)