Fall flat (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fall flat</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for flop that I've seen before include "Failure - loll" , "Collapse loosely - total failure" , "Fall clumsily, liked failed play" , "Total failure; fall heavily" , "No success" .)
(Other definitions for bomb that I've seen before include "Drop" , "not to be hit!" , "Exploding device" , "Explosive weapon" , "Flop - load of money" .)