Sex at home without love — it wears things out (7)
I believe the answer is:
'it wears things out' is the definition.
The definition suggests a singular noun which matches the answer.
'sex at home without love' is the wordplay.
'sex' becomes 'eros' (I can't explain this - if you can you should give a lot more credence to this answer).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'love' becomes 'o' (love means zero in tennis).
'in' going around 'o' is 'ion'.
Can you help me to learn more?
(Other definitions for erosion that I've seen before include "The gradual wearing away by weather" , "Abrasion" , "Process of wearing away, by water or time" , "dying away" , "Gradual decline" .)