Spymaster I tip for position in the field (3-3)
I believe the answer is:
mid off
'position in the field' is the definition.
(I've seen this before)
'spymaster i tip' is the wordplay.
'spymaster' becomes 'M' (M is the head of MI6 in James Bond).
'tip' becomes 'doff' (I've seen this in another clue).
'm'+'i'+'doff'='MID-OFF'
'for' acts as a link.
(Other definitions for mid off that I've seen before include "Cricket fielding position" , "man in field" , "Position in the field" , "Fielder near bowler (usually)" .)