She takes a mere trice to get finished (3)

'she' is the definition.

'a mere trice to get finished' is the wordplay.
I cannot quite see how this works, but
'a' is found in the answer.
'get' could be 'be' ('get' can mean 'come to be') and 'be' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

'takes' acts as a link.

Can you help me to learn more?