Suspect provided that case of felony (4)
I believe the answer is:
iffy
'suspect' is the definition.
(both can mean dubious)
'provided that case of felony' is the wordplay.
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'that case of' says to hollow out the word (remove centre letters) (outsides of).
'felony' with its centre removed is 'fy'.
'if'+'fy'='IFFY'
(Other definitions for iffy that I've seen before include "Not to be trusted" , "Full of uncertainty" , "Informally dubious or uncertain" , "Unsure" , "Dubious (colloq.)" .)