Forces repaired artwork on wall (6)
I believe the answer is:
fresco
'artwork on wall' is the definition.
(a fresco might be painted on a wall)
'forces repaired' is the wordplay.
'repaired' is an anagram indicator.
'forces' is an anagram of 'FRESCO'.
(Other definitions for fresco that I've seen before include "Artwork" , "Painting done in wet plaster" , "Mode of wall painting" , "Picture painted on wall or ceiling before plaster is dry" , "Artistic work" .)