Instrument playing shortly after bugle's entrance (7)
I believe the answer is:
bassoon
'instrument' is the definition.
(type of musical instrument)
'playing shortly after bugle's entrance' is the wordplay.
'playing' becomes 'as' (I've seen this in other clues).
'shortly' becomes 'soon' (synonyms).
'after' means one lot of letters go next to another.
'bugle's entrance' becomes 'b' (I can't justify this - if you can you should give a lot more credence to this answer).
'as'+'soon'='assoon'
'assoon' put after 'b' is 'BASSOON'.
Can you help me to learn more?
(Other definitions for bassoon that I've seen before include "Low wind instrument" , "Instrument heard by Wedding-Guest" , "wind player" , "So-so ban on the instruments" , "Tenor of the oboe family" .)