Surface defect ruined the Polo (7)
I believe the answer is:
pothole
'surface defect' is the definition.
The definition and answer can be both natural objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'ruined the polo' is the wordplay.
'ruined' indicates an anagram.
'the'+'polo'='thepolo'
'thepolo' is an anagram of 'POTHOLE'.
Can you help me to learn more?
(Other definitions for pothole that I've seen before include "Deep water-made cave, pit in road" , "Damage to road" , "Effect of subsidence" , "that can be problem when driving" , "Deep water-carved cave" .)