Top mine's distributed, but only to family members? (8)

I believe the answer is:

nepotism

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'only to family members?' is the definition.
I can't judge whether this definition defines the answer.

'top mine's distributed' is the wordplay.
'distributed' indicates anagramming the letters.
'top'+'mines'='topmines'
'topmines' anagrammed gives 'NEPOTISM'.

'but' is the link.

Can you help me to learn more?

(Other definitions for nepotism that I've seen before include "Favouring family over others" , "Undue partiality" , "Pro-family bias" , "Favouritism shown to relatives by those in power" , "Taking on family" .)

I've seen this clue in The Irish Times.

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