What’s in region of France is not always there (2-3)
I believe the answer is:
on-off
'not always there' is the definition.
(on-off can mean irregular or sporadic)
'what's in region of france' is the wordplay.
'what's in' means to look at the middle letters.
'region' becomes 'zone' (zone is a kind of region).
'france' becomes 'f'.
The centre of 'zone' is 'on'.
'on'+'of'+'f'='ON-OFF'
'is' is the link.
(Other definitions for on-off that I've seen before include "Discontinuous" , "in bursts" .)