Look a key part for a top actor (5)
I believe the answer is:
stare
'look' is the definition.
(staring is a kind of looking)
'a key part for a top actor' is the wordplay.
'a key part' becomes 'e' (I can't justify this - if you can you should give a lot more credence to this answer).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'a top actor' becomes 'star' (as in the star of a film).
'e' put after 'star' is 'STARE'.
Can you help me to learn more?
(Other definitions for stare that I've seen before include "Look with fixed eyes" , "Look hard" , "Gawp" , "Rates (anag.)" , "Long fixed look" .)