Cleaner computer network limiting core of late fraud (9)
I believe the answer is:
charlatan
'fraud' is the definition.
(thesaurus)
'cleaner computer network limiting core of late' is the wordplay.
'cleaner' becomes 'char' (charwoman is a type of cleaner).
'computer network' becomes 'lan' (LAN is an example).
'limiting' indicates putting letters inside.
'core of' means to look at the middle letters.
The middle of 'late' is 'at'.
'lan' enclosing 'at' is 'latan'.
'char'+'latan'='CHARLATAN'
(Other definitions for charlatan that I've seen before include "Flamboyant deceiver, mountebank" , "imposter" , "Trickster" , "Person who falsely claims to be an expert" , "Quack doctor" .)