Position in which half of Russian jets take off (3-3)
I believe the answer is:
mid-off
'position' is the definition.
(cricketing position)
'half of russian jets take off' is the wordplay.
'half of' indicates taking half.
'russian jets' becomes 'MiGs' (plane manufactured by the company MiG).
'take off' becomes 'doff' (as in to doff one's hat).
'migs' cut in half is 'mi'.
'mi'+'doff'='MID-OFF'
'in which' acts as a link.
(Other definitions for mid-off that I've seen before include "Cricket fielding position" , "Position in the field" , "Someone in field" .)