String trio start on Chardonnay perhaps (5)
I believe the answer is:
twine
'string' is the definition.
('twine' can be a synonym of 'string')
'trio start on chardonnay perhaps' is the wordplay.
'start on' indicates taking the first letters (I've seen 'starts on' mean this).
'chardonnay perhaps' becomes 'wine' (chardonnay is a kind of wine).
The initial letter of 'trio' is 't'.
't'+'wine'='TWINE'
(Other definitions for twine that I've seen before include "Tough string" , "Coil" , "String of twisted fibres" , "can get into knots" , "weaving" .)