Pair up the words so that the two words in each pair can be preceded or followed by the same word to make a longer word or two-word phrase. Then find a third word which also makes a word or phrase with the same preceding or following word. This is highly ambiguous, but if you do it correctly then each third word is used twice:
jumping \ lumber -JACK BLACK < night -GUARD trigger / /guitar ELECTRIC-meter \CIRCUIT \ ice -BREAKER path / /barrel GUN-powder \DOG \ rasp -BERRY straw / /pound QUARTER-staff >FINAL SEMI-quaver \skim cayenne \ whole -PEPPER GREEN < kidney -BEAN string / /computer MICRO-scope >LIGHT SUN-beam \down /machine TIME-zone \WASTE \ flash -PAPER manila / /potato WHITE-wash \WATER \ not -GATE star /
Sort the third words alphabetically, concatenate them and extract the letters with the indices stated in the puzzle:
then randomly anagram to give the answer CACKLE.