Making a comeback, Alexander Armstrong wraps special (4)
I believe the answer is:
rare
'special' is the definition.
(I've seen this in another clue)
'making a comeback alexander armstrong wraps' is the wordplay.
'making a comeback' says the letters should be written in reverse.
'wraps' indicates the answer is hidden within the clue (wrap can mean cover or conceal).
'erar' is hidden within 'alexander armstrong'.
'erar' reversed gives 'RARE'.
(Other definitions for rare that I've seen before include "Unusual - exquisite" , "Seldom seen or met" , "Unusual(ly fine)" , "of low density" , "Might steak be" .)