Year-after-year (9)
I believe the answer is:
perennial
'year-after-year' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for perennial that I've seen before include "Perpetual" , "Plant that lives for a number of years" , "Constantly recurring like some plants" , "never failing" , "Constant" .)