View troops occupying isthmus (8)
I believe the answer is:
panorama
'view' is the definition.
(synonyms)
'troops occupying isthmus' is the wordplay.
'troops' becomes 'or' (military abbreviation for other ranks).
'occupying' means one lot of letters goes inside another.
'isthmus' becomes 'panama' (I've seen this before).
'or' inserted within 'panama' is 'PANORAMA'.
(Other definitions for panorama that I've seen before include "Am on a par (anag)" , "Wide view of region" , "Extensive all-round view" , "Impressive view" , "Wide view (from BBC TV?)" .)