Poles interceding in characteristic passage (7)
I believe the answer is:
transit
'passage' is the definition.
(synonyms)
'poles interceding in characteristic' is the wordplay.
'poles' becomes 'ns' (North and South poles).
'interceding in' is an insertion indicator.
'characteristic' becomes 'trait' (I've seen this before).
'ns' inserted inside 'trait' is 'TRANSIT'.
(Other definitions for transit that I've seen before include "Passage of a planet across the sun's disc" , "Movement (of goods)" , "Pass across" , "The process of going or passing - sic . . . . . . . gloria mundi" , "Conveyance of goods or people - tin star (anag)" .)