Boy band played trumpets on a record (4)
I believe the answer is:
blue
'played trumpets on a record' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives sometimes mean the same thing.
'boy band' is the wordplay.
'boy' becomes 'b' (abbreviation used in schools).
'band' becomes 'lue' (I can't justify this - if you can you should believe this answer much more).
'b'+'lue'='BLUE'
Can you help me to learn more?
(Other definitions for blue that I've seen before include "Sky-coloured" , "Sea colour" , "Dismal" , "Colour of depression" , "Vulgar" .)