Positions of machine-guns swivelling, then heading for heart (5)
I believe the answer is:
nests
'positions' is the definition.
The definition and answer can be both locations as well as being plural nouns.
Maybe there's a link between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for nests that I've seen before include "Bird houses" , "Eyries" , "Places to rear the young?" , "Birds' homes" , "Settles comfortably into, as birds do" .)