Second volume ending in case for advocate (4)
I believe the answer is:
move
'advocate' is the definition.
(thesaurus)
'second volume ending in case' is the wordplay.
'second' becomes 'mo' (both are short periods of time).
'volume' becomes 'v' (abbreviation for volume in book titles).
'ending in' suggests the final letters.
The last letter of 'case' is 'e'.
'mo'+'v'+'e'='MOVE'
'for' is the link.
(Other definitions for move that I've seen before include "Travel - propose" , "Shift" , "Stir emotions" , "Go, transport" , "Change location" .)