Destroy nasty coat whatever the consequences (2,3,4)
I believe the answer is:
at any cost
'whatever the consequences' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'destroy nasty coat' is the wordplay.
'destroy' indicates anagramming the letters (I've seen this in other clues).
'nasty'+'coat'='nastycoat'
'nastycoat' anagrammed gives 'AT ANY COST'.
Can you help me to learn more?
(Other definitions for at any cost that I've seen before include "Regardless of the price to pay" , "whatever the damage" .)