Hollywood star once right to sign lover’s heart in tree (5)
I believe the answer is:
novak
'hollywood star once right to sign' is the definition.
I can't judge whether this definition defines the answer.
'lover's heart in tree' is the wordplay.
'heart' indicates the central letters.
'in' is an insertion indicator.
'tree' becomes 'noak' (I can't explain this - if you can you should give a lot more credence to this answer).
The central letter of 'lover' is 'v'.
'v' going within 'noak' is 'NOVAK'.
Can you help me to learn more?
(Another definition for novak that I've seen is " Female film star, Kim".)