Dressings show how old the orchestra players are (8)
I believe the answer is:
bandages
'dressings' is the definition.
(bandage is a kind of dressing)
'players are' is the wordplay.
'players' becomes 'band' (group playing music).
'are' becomes 'ages' (I can't explain this - if you can you should give a lot more credence to this answer).
'band'+'ages'='BANDAGES'
'show how old the orchestra' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for bandages that I've seen before include "Wound wrappings" , "first-aid items" , "Wrappings for wounds" , "forms of protection after accident" .)