Suspect cheery rat — of this? (9)
I believe the answer is:
treachery
'this?' is the definition.
The definition suggests a singular noun which matches the answer.
'suspect cheery rat' is the wordplay.
'suspect' is an anagram indicator (a suspicious or unusual spelling).
'cheery'+'rat'='cheeryrat'
'cheeryrat' anagrammed gives 'TREACHERY'.
'of' is the link.
Can you help me to learn more?
(Other definitions for treachery that I've seen before include "Perfidy" , "Treason" , "Betrayal of trust" , "lack of loyalty" , "Double-dealing" .)