So nicely balanced, my lime crystal shattered (13)

I believe the answer is:

symmetrically

'so nicely balanced' is the definition.
(in a balanced or symmetrical way)

'my lime crystal shattered' is the wordplay.
'shattered' is an anagram indicator.
'my'+'lime'+'crystal'='mylimecrystal'
'mylimecrystal' anagrammed gives 'SYMMETRICALLY'.

I've seen this clue in The Times.

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