Remain with server in shop (6)
I believe the answer is:
betray
'shop' is the definition.
(I've seen this before)
'remain with server' is the wordplay.
'remain' becomes 'be' (I've seen this in other clues).
'with' is a charade indicator (letters next to each other).
'server' becomes 'tray' (I've seen this in another clue).
'be'+'tray'='BETRAY'
'in' acts as a link.
(Other definitions for betray that I've seen before include "Break confidence" , "Cheat on" , "Double-cross, sell out" , "Reveal (intentionally or unintentionally)" , "Be disloyal; reveal" .)