Eyesores yet to be improved on board (5)
I believe the answer is:
styes
'eyesores' is the definition.
(I've seen this before)
'yet to be improved on board' is the wordplay.
'to be improved' is an anagram indicator.
'on' is an insertion indicator.
'board' becomes 'ss' (I've seen this in other clues).
'yet' anagrammed gives 'tye'.
'tye' put inside 'ss' is 'STYES'.
(Other definitions for styes that I've seen before include "gatherings" , "Eye troubles" , "Eyesores" , "Pig pens" , "Eyelid swellings" .)