Cause of furrowed brows or wires getting tangled (7)
I believe the answer is:
worries
'cause of furrowed brows' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.
'or wires getting tangled' is the wordplay.
'getting tangled' is an anagram indicator.
'or'+'wires'='orwires'
'orwires' anagrammed gives 'WORRIES'.
Can you help me to learn more?
(Other definitions for worries that I've seen before include "Concerns" , "Sources of anxiety" .)