Look for arches in need of repair (6)
I believe the answer is:
search
'look for' is the definition.
(synonyms)
'arches in need of repair' is the wordplay.
'in need of repair' indicates an anagram.
'arches' is an anagram of 'SEARCH'.
(Other definitions for search that I've seen before include "thorough examination" , "investigation . . . ." , "Forage, quest" , "Scour, seek" , "Look for something or someone, perhaps chaser" .)