Each reach turned out to be a pain (7)
I believe the answer is:
earache
'a pain' is the definition.
(I know that earache is a type of ache)
'each reach turned out' is the wordplay.
'each' becomes 'ea' (abbreviation).
'turned out' indicates an anagram (turn out can mean to organise).
'reach' anagrammed gives 'rache'.
'ea'+'rache'='EARACHE'
'to be' is the link.
(Other definitions for earache that I've seen before include "Pain for listener" , "Pain in aural organ" , "Pain in the hearing organ" , "Otic pain" , "listener's discomfort" .)