An actor's "aside"? (5)

I believe the answer is:

apart

I'm a little stuck... Click here to teach me about this clue!

Here is my best explanation:

'aside?' is the definition.
('apart' can be a synonym of 'aside')

'an actor's' is the wordplay.
'an' becomes 'a'.
'actor' becomes 'part' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'part'='APART'

Can you help me to learn more?