Rings up to gas about everything (5)
I believe the answer is:
calls
'rings up' is the definition.
(I've seen this in another clue)
'gas about everything' is the wordplay.
'gas' becomes 'cs' (short for 2-chlorobenzalmalononitrile).
'about' means one lot of letters goes inside another.
'everything' becomes 'all' (all things).
'cs' going around 'all' is 'CALLS'.
'to' is the link.
(Other definitions for calls that I've seen before include "Makes a social visit" , "Speaks to attract someone's attention" , "Pays a visit" , "Names" , "Shouts" .)