Too early to be unaffected surrounding tamer reversal (9)
I believe the answer is:
premature
'too early' is the definition.
(I've seen this before)
'unaffected surrounding tamer reversal' is the wordplay.
'unaffected' becomes 'pure' (I am not sure about this - if you are sure you should believe this answer much more).
'surrounding' indicates putting letters inside.
'reversal' says the letters should be written backwards.
'tamer' in reverse letter order is 'remat'.
'pure' going around 'remat' is 'PREMATURE'.
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for premature that I've seen before include "Occurring before the expected time" , "Too soon to cause me rapture" , "Too soon or too hasty" , "Untimely" , "Early" .)