Drink beer occasionally -- excellent (5)
I believe the answer is:
super
'excellent' is the definition.
(I've seen this before)
'drink beer occasionally' is the wordplay.
'drink' becomes 'sup' (to sup is to drink).
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
The alternating letters of 'beer' are 'er'.
'sup'+'er'='SUPER'
(Other definitions for super that I've seen before include "Peerless" , "Excellent - small-part actor" , "Prefix meaning over-excellent!" , "Gushily great, excellent" , "Great; wonderful" .)