Flop, failing in amorous situation could occur initially ... (6)
I believe the answer is:
fiasco
'flop' is the definition.
(thesaurus)
'failing in amorous situation could occur initially' is the wordplay.
'initially' indicates taking the first letters.
The first letters of 'failing in amorous situation could occur' is 'FIASCO'.
(Other definitions for fiasco that I've seen before include "An absolute mess, what a farce" , "Abject failure" , "Humiliating disaster" , "Total catastrophe" , "Ignominious result" .)