Live portrayal finally capturing one Shakespeare character (5)
I believe the answer is:
ariel
'shakespeare character' is the definition.
(Ariel is a character in The Tempest)
'live portrayal finally capturing one' is the wordplay.
'live' becomes 'are' (I've seen this before).
'finally' says to take the final letters.
'capturing' means one lot of letters goes inside another.
'one' becomes 'I' (Roman numeral).
The last letter of 'portrayal' is 'l'.
'are'+'l'='arel'
'arel' going around 'i' is 'ARIEL'.
(Other definitions for ariel that I've seen before include "Swallows" , "Shakespearian sprite - Uranus satellite - gazelle" , "fairy sign" , "Fairy in "The Tempest"" , "Disney character" .)