Northern isle voided tense recount (7)
I believe the answer is:
narrate
'recount' is the definition.
(synonyms)
'northern isle voided tense' is the wordplay.
'northern' is a reversal indicator (in a down clue, letters go up or 'north').
'isle' becomes 'arran' (Isle of Arran in Scotland).
'voided' says to hollow out the word (remove centre letters) (void can mean to empty out).
'tense' with its centre taken out is 'te'.
'arran' reversed gives 'narra'.
'narra'+'te'='NARRATE'
(Other definitions for narrate that I've seen before include "Relate, recount" , "Tell story,recount" , "Relay" , "Provide commentary" , "'Recount, tell (7)'" .)