Board welcomes all willing to learn (9)
I believe the answer is:
teachable
'willing to learn' is the definition.
(willing to be taught)
'board welcomes all' is the wordplay.
'board' becomes 'table' (both can mean food).
'welcomes' indicates putting letters inside (in sense of 'invites in').
'all' becomes 'each' (similar in meaning).
'table' going around 'each' is 'TEACHABLE'.
(Other definitions for teachable that I've seen before include "interested in education" , "head's description of promising pupils" , "ready to educate" , "Ready and willing to be taught" , "Ready for instruction" .)