Muscles in disorder, initially showing lack of coordination (10)

'lack of coordination' is the definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Perhaps you can see an association between them that I don't see?

'muscles in disorder initially showing' is the wordplay.
'disorder' is an anagram indicator (a disordered version of the letters).
'initially' suggests taking the first letters.
The initial letter of 'showing' is 's'.
'muscles'+'in'='musclesin'
'musclesin' anagrammed gives 'clumsines'.
'clumsines'+'s'='CLUMSINESS'

Can you help me to learn more?