Aid organised by a Welshman (3)
I believe the answer is:
dai
'a welshman' is the definition.
(Welsh name)
'aid organised' is the wordplay.
'organised' indicates an anagram.
'aid' anagrammed gives 'DAI'.
'by' acts as a link.
(Other definitions for dai that I've seen before include "Perhaps man in Cardiff" , "Welshman" , "Welsh male name" , "Lloyd George?" , "Welshman's name" .)