Decoration, though denied second top award in pageantry (4)
I believe the answer is:
pomp
'pageantry' is the definition.
(I've seen this in another clue)
'decoration though denied second top award in' is the wordplay.
'decoration though' becomes 'pop' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'denied' suggests deleting specific letters (the word is denied or deprived of some letters).
'second top' becomes 'o' (ond letter of 'top').
'award' becomes 'OM' (order of merit).
'in' indicates putting letters inside.
'om' with 'o' taken out is 'm'.
'pop' enclosing 'm' is 'POMP'.
Can you help me to learn more?
(Other definitions for pomp that I've seen before include "Self-importance" , "Excessive ceremony" , "Ceremonial grandeur" , "Ostentatious ceremony" , "Ceremony and splendour" .)