Mates playing new viola part? (6)
I believe the answer is:
stamen
'viola part?' is the definition.
'stamen' can be an answer for 'part?' (I have seen 'Part of flower' mean 'stamen' so perhaps 'part' could also mean 'stamen'). I am unsure of the 'viola' bit.
'mates playing new' is the wordplay.
'playing' indicates anagramming the letters.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'mates' is an anagram of 'stame'.
'stame'+'n'='STAMEN'
Can you help me to learn more?
(Other definitions for stamen that I've seen before include "Male ditto" , "Part of flower producing pollen" , "Manet's (anag.)" , "Pollen-bearing part of a flower" , "Flower pollen carrier" .)