There is nothing amiss in such speculations (8)
I believe the answer is:
theories
'such speculations' is the definition.
The definition and answer can be both related to thinking as well as being plural nouns.
Perhaps you can see a link between them that I don't see?
'there is nothing amiss' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'amiss' indicates anagramming the letters.
'there'+'is'+'o'='thereiso'
'thereiso' with letters rearranged gives 'THEORIES'.
'in' is the link.
Can you help me to learn more?
(Other definitions for theories that I've seen before include "General principles or possibilities" , "Assumptions" , "Conjectures" , "premises?" , "Abstract principles" .)