Everything considered, it appears best (7)
I believe the answer is:
overall
'it appears best' is the definition.
The definition suggests a singular noun which matches the answer.
'everything considered' is the wordplay.
I cannot really understand how this works, but
'everything' could be 'all' (all things) and 'all' is present in the answer.
The remaining letters 'over' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for overall that I've seen before include "All over in general way" , "Taking everything into account" , "Protective garment worn over ordinary clothes" , "Workman's garment worn to protect other clothing (7)" , "protector" .)