Instruments, but as played (5)
I believe the answer is:
tubas
'instruments' is the definition.
(I've seen this in another clue)
'but as played' is the wordplay.
'played' indicates an anagram (letters playing around).
'but'+'as'='butas'
'butas' with letters rearranged gives 'TUBAS'.
(Other definitions for tubas that I've seen before include "Large brass instruments" , "What some musicians" .)