Unknown pianist hugging unknown tree (5-5)

I believe the answer is:

ylang-ylang

'tree' is the definition.
(ylang-ylang is a kind of tree)

'unknown pianist hugging unknown' is the wordplay.
'unknown' becomes 'y' (algebra).
'pianist' becomes 'langlang' (Chinese pianist).
'hugging' means one lot of letters goes inside another.
'unknown' becomes 'y' (algebra).
'langlang' enclosing 'y' is 'langylang'.
'y'+'langylang'='YLANG-YLANG'

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app