Grindr is one (3)
I believe the answer is:
app
'grindr is one' is the definition.
(I know that Grindr is a app)
This is the entire clue.
(Other definitions for app that I've seen before include "bit of software" , "Software for mobile devices, in short" , "Software program for a mobile device" , "Software item" , "Program for a smart phone, in short" .)