Each woman endlessly causes pain (7)
I believe the answer is:
earache
'pain' is the definition.
(earache is a kind of pain)
'each woman endlessly' is the wordplay.
'each' becomes 'ea' (abbreviation).
'woman endlessly' becomes 'rache' (I can't justify this - if you can you should believe this answer much more).
'ea'+'rache'='EARACHE'
'causes' acts as a link.
Can you help me to learn more?
(Other definitions for earache that I've seen before include "otitis" , "Aural discomfort" , "Form of torture" , "complaint to The Listener" , "Lughole pain" .)