Access computer using firm’s symbol and name (3,2)
I believe the answer is:
log on
'access computer' is the definition.
(as in logging on to a computer)
'firm's symbol and name' is the wordplay.
'firm's symbol' becomes 'logo' (a corporate symbol).
'and' means one lot of letters go next to another.
'name' becomes 'n' (common abbreviation e.g. on forms).
'logo'+'n'='LOG ON'
'using' is the link.
(Other definitions for log on that I've seen before include "Gain computer access" , "Enter online program" , "Prepare to surf, perhaps?" , "Access the Internet" , "Sign in to a computer" .)