Actor learning lines in the centre (5)
I believe the answer is:
loren
'actor' is the definition.
(I know that Actor is a type of actor\nI know that Sophia Loren is a Actor\nTherefore, Sophia Loren is a actor)
'learning lines in the centre' is the wordplay.
'learning' becomes 'lore' (both can mean tradition or knowledge).
'in the centre' means to look at the middle letters.
The middle of 'lines' is 'n'.
'lore'+'n'='LOREN'
(Other definitions for loren that I've seen before include "Sofia, Italian film actress" , "Sophia -, Ital. actress" , "Sophia --, Italian film actress" , "See 15" , "Sophia - - (film star)" .)