Nervous laugh (6)
'nervous laugh' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for giggle that I've seen before include "Laugh affectedly" , "Laugh in a silly manner" , "Foolish or nervous laugh" , "Nervous or silly laughter" , "Laugh nervously" .)
'nervous laugh' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for titter that I've seen before include "Suppressed snigger" , "Stifled laugh" , "Stifled giggle" , "A high-pitched nervous laugh" , "Nervous restrained laugh" .)