Stunner modelled again making comeback? (5)
I believe the answer is:
taser
'stunner' is the definition.
(I've seen this before)
'modelled again making comeback?' is the wordplay.
'modelled again' becomes 'resat' ('sat' can be a synonym for 'modelled' so perhaps 'resat' is OK for 'modelled again').
'making comeback?' says the letters should be written backwards.
'resat' back-to-front is 'TASER'.
(Other definitions for taser that I've seen before include "police weapon introduced" , "shocker" , "A shocking thing" , "The weapon delivers a temporary paralysing electric shock" , "Weapon used to deliver a temporarily paralysing electric shock" .)