Left by end of fireworks display (5)
I believe the answer is:
sport
'display' is the definition.
(to sport an item is to wear or display it)
'left by end of fireworks' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'by' means one lot of letters go next to another.
'end of fireworks' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'port' put after 's' is 'SPORT'.
Can you help me to learn more?
(Other definitions for sport that I've seen before include "Abnormal" , "Game; display" , "form of exercise?" , "Fun; wear" , "Wear - game - generous type" .)