Trooper apparently securing work (5)
I believe the answer is:
opera
'work' is the definition.
(I've seen this before)
'trooper apparently securing' is the wordplay.
'securing' says the answer is hidden in the clue.
'OPERA' is hidden within 'trooper apparently'.
(Other definitions for opera that I've seen before include "Dramatic genre" , "could be soap" , "Verdi work?" , "Macbeth, perhaps" , "Eg, La forza del destino" .)