Commander Mike to hand over navigational device (7)
I believe the answer is:
compass
'navigational device' is the definition.
(instrument which helps with navigation)
'commander mike to hand over' is the wordplay.
'commander' becomes 'co'.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'to hand over' becomes 'pass'.
'co'+'m'+'pass'='COMPASS'
(Other definitions for compass that I've seen before include "Range, area" , "Instrument for determining direction from magnetic needle" , "Orienteering instrument" , "Navigational instrument" , "Direction finding instrument - range" .)