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 the answer is hidden within the clue.
'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" .)