In a perfect world, I would start to embrace mate (7)
I believe the answer is:
ideally
'in a perfect world' is the definition.
(I've seen this before)
'i would start to embrace mate' is the wordplay.
'i would' becomes 'id'.
'start to' indicates taking the first letters.
'mate' becomes 'ally' (I've seen this before).
The initial letter of 'embrace' is 'e'.
'id'+'e'+'ally'='IDEALLY'
(Other definitions for ideally that I've seen before include "In the most perfect way" , "for preference" , "in theory" , "Perfectly; most suitably" , "In a perfect world, the best possible situation" .)