Support playwright retaining current share (10)
I believe the answer is:
proportion
'support playwright' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'retaining current share' is the wordplay.
'retaining current' becomes 'pro' (I can't justify this - if you can you should give a lot more credence to this answer).
'share' becomes 'portion' ('portion' can be a synonym of 'share').
'pro'+'portion'='PROPORTION'
Can you help me to learn more?
(Other definitions for proportion that I've seen before include "balance" , "Part - one needs a sense of it" .)