Clue: regularly pilfer small drinks (7)
I believe the answer is:
tipples
'drinks' is the definition.
(tipple is a kind of drink)
'clue regularly pilfer small' is the wordplay.
'clue' becomes 'tip' (I've seen this before).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'small' becomes 's' (abbreviation - e.g. clothes size).
The alternate letters of 'pilfer' are 'ple'.
'tip'+'ple'+'s'='TIPPLES'
(Other definitions for tipples that I've seen before include "Drinks moderately" , "Is in the habit of drinking alcohol" , "Drinks alcohol regularly" .)