It's played in honour of leader (4)
I believe the answer is:
oboe
'it's played' is the definition.
(oboe is a kind of musical instrument)
'in honour of leader' is the wordplay.
'in' indicates putting letters inside.
'honour' becomes 'OBE' (Order of the British Empire).
'leader' indicates taking the first letters.
The first letter of 'of' is 'o'.
'obe' enclosing 'o' is 'OBOE'.
(Other definitions for oboe that I've seen before include "Double-reed woodwind" , "Instrument used in 1d" , "Slender double-reed instrument" , "Cor anglais in its family" , "Double-reeded woodwind instrument" .)