Forward in expertise (4)
I believe the answer is:
pert
'forward' is the definition.
(both can mean cheeky or disrespectful)
'in expertise' is the wordplay.
'in' indicates a hidden word.
'PERT' can be found hidden inside 'expertise'.
(Other definitions for pert that I've seen before include "Saucy, lively" , "Jaunty" , "Impudent, cheeky" , "Irreverent or saucy" , "Saucy, maybe brash" .)