Can be heard to click, or possibly give a scream! (7)
I believe the answer is:
cameras
'can be heard to click' is the definition.
I can't tell whether this defines the answer.
'possibly give a scream' is the wordplay.
'possibly' is an anagram indicator.
'give' says to put letters next to each other.
'a' put next to 'scream' is 'ascream'.
'ascream' with letters rearranged gives 'CAMERAS'.
'or' is the link.
Can you help me to learn more?
(Other definitions for cameras that I've seen before include "Light-proof boxes" , "television equipment" , "Image recorders" .)