Extreme colour acquires name (7)
I believe the answer is:
violent
'extreme' is the definition.
(I've seen this before)
'colour acquires name' is the wordplay.
'colour' becomes 'violet' (violet is a kind of colour).
'acquires' means one lot of letters goes inside another.
'name' becomes 'n' (common abbreviation e.g. on forms).
'violet' going around 'n' is 'VIOLENT'.
(Other definitions for violent that I've seen before include "Strong - destructive" , "Tending to use intimidatory force" , "Extreme(ly aggressive)" , "Wild - not evil (anag)" , "not peaceful either" .)