Cliff's drinking partner and friend, as a rule (8)
I believe the answer is:
normally
'as a rule' is the definition.
(I've seen this before)
'cliff's drinking partner and friend' is the wordplay.
'cliff's' becomes 'orm' (I can't explain this - if you can you should believe this answer much more).
'drinking' is an insertion indicator.
'partner' becomes 'n'.
'and' says to put letters next to each other.
'friend' becomes 'ally' (an ally is a friend or supporter).
'n'+'ally'='nally'
'orm' going into 'nally' is 'NORMALLY'.
Can you help me to learn more?
(Other definitions for normally that I've seen before include "Ordinarily, usually" , "In the usual way" , "In the ordinary or typical way" , "Naturally" , "in standard fashion" .)