We need a new one annually (4)
I believe the answer is:
year
'new one annually' is the definition.
I can't tell whether this definition defines the answer.
'we need a' is the wordplay.
I cannot really see how this works, but
'a' is found in the answer.
The remaining letters 'yer' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for year that I've seen before include "26 fortnights" , "Pupil group" , "Orbital period" , "Manage" , "See 9" .)