Navigational calculation of body count? (4,9)
I believe the answer is:
dead reckoning
'navigational calculation' is the definition.
(I've seen this before)
'body count?' is the wordplay.
I cannot really understand how this works, but
'body' could be 'dead' (synonyms) and 'dead' is found in the answer.
'count?' could be 'reckoning' ('reckoning' can be a synonym of 'count') and 'reckoning' is found within the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for dead reckoning that I've seen before include "Estimation of position at sea by reference to course steered and distance run" , "Navigation without using the stars" , "Method of estimating ship's or plane's location" , "One way to chart" , "can tell you where you are" .)