Kind of tea written on one board (10)
I believe the answer is:
charitable
'kind' is the definition.
(thesaurus)
'tea written on one board' is the wordplay.
'tea' becomes 'char' (I've seen this before).
'written on' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'board' becomes 'table' ('table' can be a synonym of 'board').
'char'+'i'+'table'='CHARITABLE'
'of' acts as a link.
(Other definitions for charitable that I've seen before include "Thoughtful" , "Inspired by the will to do good for others" , "Big-hearted" , "Benevolent" , "Kind" .)