Fundamental racial solution holds key (7)
I believe the answer is:
radical
'fundamental' is the definition.
(I've seen this before)
'racial solution holds key' is the wordplay.
I cannot really see how this works, but
'key' could be 'd' (musical key) and 'd' is found in the answer.
an anagram of 'racial' is 'raical' which is located in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for radical that I've seen before include "Dial car in order to be drastic" , "Subversive" , "Holding extreme political views" , "Going to the roots, fundamental as change may be" , "One holding strong reformist views" .)