One I would help (3)
I believe the answer is:
aid
'help' is the definition.
(synonyms)
'one i would' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'i would' becomes 'I'd'.
'a'+'id'='AID'
(Other definitions for aid that I've seen before include "Care and help" , "grant" , "Auxiliary" , "A hand" , "assistant" .)