It shows all-round lack of scoring ability (3)
I believe the answer is:
nil
'it shows all-round lack of scoring ability' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for nil that I've seen before include "duck" , "Nothing, no value" , "Zero, no score" , "0" , "Score of nought" .)