Eternal lover I flogged, ending in woe (6)
I believe the answer is:
isolde
'eternal lover' is the definition.
'isolde' can be an answer for 'lover' (one of the lovers in the opera Tristan and Isolde). I am not certain of the 'eternal' bit.
'i flogged ending in woe' is the wordplay.
'flogged' becomes 'sold' (flog can mean to sell).
'ending in' suggests the final letters.
The last letter of 'woe' is 'e'.
'i'+'sold'+'e'='ISOLDE'
Can you help me to learn more?
(Other definitions for isolde that I've seen before include "Tristan and ... (Wagner opera)" , "Soiled like Tristan's lover" , "Irish princess" , "Soiled like Tristram's girl friend" , "Tristan and . . . . . . (medieval romance)" .)