Constant change affecting most fads and tastes (9)
I believe the answer is:
steadfast
'constant' is the definition.
(similar in meaning)
'change affecting most fads and tastes' is the wordplay.
I cannot really see how this works, but
an anagram of 'fads' is 'dfas' which is located in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for steadfast that I've seen before include "Fixed, unyielding" , "Constant; true" , "Strong" , "Resolute, unwavering" , "Dedicated" .)