Information of French work inside (4)
I believe the answer is:
dope
'information' is the definition.
(dope is a kind of information)
'of french work inside' is the wordplay.
'of french' becomes 'de' ('of' in French).
'work' becomes 'op' (abbreviation for opus).
'inside' is an insertion indicator.
'de' enclosing 'op' is 'DOPE'.
(Other definitions for dope that I've seen before include "Weed perhaps" , "Information, fool" , "Drug - information" , "Lowdown; drugs (informal)" , "The idiot's a drug" .)