Lose the thread in rancour (6)
I believe the answer is:
hatred
'rancour' is the definition.
The answer and definition can be both feelings as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'lose the thread' is the wordplay.
'lose' indicates anagramming the letters (I've seen 'lost' mean this).
'thread' with letters rearranged gives 'HATRED'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for hatred that I've seen before include "Animus" , "Intense dislike" , "Great dislike" , "Abhorrence, detestation" , "'Loathing, enmity (6)'" .)