Fish have them and musicians play them (6)
I believe the answer is:
scales
This clue could be a double definition.
'fish have them' is the first definition.
I know that 'fish' relates to this answer.
'musicians play them' is the second definition.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for scales that I've seen before include "The practice of music" , "Zodiac sign < covering fish" , "Weighing machine" , "Pair of balances" , "Instruments for weighing things" .)