It's concerning to Wellington, how one reacts to The Crash (6)
I believe the answer is:
reboot
'one reacts to the crash' is the definition.
I can't judge whether this defines the answer.
'it's concerning to wellington' is the wordplay.
'it's concerning' becomes 're' (both can mean on a particular topic).
'to wellington' becomes 'boot' (Wellington boots are a type of shoe).
're'+'boot'='REBOOT'
'how' is the link.
Can you help me to learn more?
(Other definitions for reboot that I've seen before include "Start notebook again" , "Recover from crash" , "Start up a computer's initial program again" , "Start (computer) again" , "Re-start up a computer's initial program" .)