Eyesore some tomfool Yankee erected first of all (4)
I believe the answer is:
stye
'eyesore' is the definition.
(I've seen this before)
'some tomfool yankee erected first of all' is the wordplay.
'first of all' suggests taking the first letters.
The initial letters of 'some tomfool yankee erected' is 'STYE'.
(Other definitions for stye that I've seen before include "Eye problem" , "Eyelid affliction" , "Eyelid sore" , "Red eye" , "Inflammation around the eye" .)