Barber shop with no work to declare (6)
I believe the answer is:
Here is my best explanation:
'barber' is the definition.
'shop with no work to declare' is the subsidiary indication.
'with no' suggests deleting specific letters.
'work' becomes 'op' (common abbreviation for 'opus').
'to declare' becomes 'aver' (averring is a kind of declaring).
'shop' with 'op' taken away is 'sh'.
(Other definitions for shaver that I've seen before include "Young lad (dated); razor", "Hair remover", "young man", "Boy < barber", "Youth", "A razor or its user", "Razor", "Electric razor", "youngster once" and "little boy".)