Call back, demanding sandwiches (4)
I believe the answer is:
name
'call' is the definition.
(as in calling or naming someone something)
'back demanding sandwiches' is the wordplay.
'back' says the letters should be written in reverse.
'sandwiches' indicates a hidden word (the answer is sandwiched in by the clue).
'eman' is hidden in the letters of 'demanding'.
'eman' in reverse letter order is 'NAME'.
(Other definitions for name that I've seen before include "Handle" , "Call; reputation" , "Designation; fame" , "Mean sort of appellation" , "Specify; famous person" .)