Poet or yokel about to make a mistake (7)
I believe the answer is:
herrick
'poet' is the definition.
(I know that Herrick is a poet)
'yokel about to make a mistake' is the wordplay.
'yokel' becomes 'hick' (synonyms).
'about' means one lot of letters goes inside another.
'to make a mistake' becomes 'err' (to err is to make an error).
'hick' enclosing 'err' is 'HERRICK'.
'or' is the link.
(Other definitions for herrick that I've seen before include "Robert --, English poet" , "Lyric poet" , "Gather ye rosebuds poet" .)