Snapchat or TikTok (3)
I believe the answer is:
app
'snapchat or tiktok' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for app that I've seen before include "Software for mobile devices, in short" , "Program for a smart phone, in short" , "Software program for a mobile device" , "Software item" , "bit of software" .)