Be anxious when losing opener for lock (5)
I believe the answer is:
tress
This might be a double definition.
'be anxious when losing opener' is the first definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'for lock' is the second definition.
(both can mean a piece of hair)
Can you help me to learn more?
(Other definitions for tress that I've seen before include "Switch" , "Rests (anag.)" , "Long piece of hair" , "Braid of hair" , "Curl - lock" .)