Shortness of balls: second over at the crease (9)
I believe the answer is:
testiness
'shortness' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'balls second over at the crease' is the wordplay.
'balls' becomes 'testes' (balls can informally mean testicles).
'second' becomes 's' (common abbreviation).
'over' is an insertion indicator.
'at the crease' becomes 'in' (cricket term).
'testes'+'s'='testess'
'testess' placed around 'in' is 'TESTINESS'.
'of' is the link.
Can you help me to learn more?
(Other definitions for testiness that I've seen before include "Irritability" , "Irascibility" .)