Switch to sailor mode (8)
I believe the answer is:
isolator
'switch' is the definition.
(I know that isolator is a type of switch)
'to sailor mode' is the wordplay.
'mode' indicates anagramming the letters (another mode or version of the letters).
'to'+'sailor'='tosailor'
'tosailor' anagrammed gives 'ISOLATOR'.
(Other definitions for isolator that I've seen before include "The curse of Crusoe" , "Switch cutting off electricity" , "Cut-off switch" , "Switch cutting off part of circuit" , "Switch cutting off power" .)