Permit secretary's physical activity (8)
I believe the answer is:
passport
'permit' is the definition.
(thesaurus)
'secretary's physical activity' is the wordplay.
'secretary's' becomes 'pas' (I've seen this in other clues).
'physical activity' becomes 'sport' (I've seen this before).
'pas'+'sport'='PASSPORT'
(Other definitions for passport that I've seen before include "Traveller's ID" , "Travel ID" , "Carte blanche" , "that may gain acceptance" , "Traveller's aid" .)