Office worker tucking into salty pistachios (6)
I believe the answer is:
typist
'office worker' is the definition.
(someone who types documents)
'tucking into salty pistachios' is the wordplay.
'tucking into' indicates a hidden word (I've seen 'tucked into' mean this).
'TYPIST' is hidden within 'salty pistachios'.
(Other definitions for typist that I've seen before include "Pre-computer office worker" , "The old-style secretary, for one" , "Skilled keyboarder" , "One using keyboard" , "Keyboard user" .)