Fresh fish secured by pub ahead of time (8)
I believe the answer is:
insolent
'fresh' is the definition.
(thesaurus)
'fish secured by pub ahead of time' is the wordplay.
'fish' becomes 'sole' (I've seen this before).
'secured by' indicates putting letters inside (I've seen this in other clues).
'pub' becomes 'inn' (I've seen this before).
'ahead of time' becomes 't' (I've seen this in other clues).
'sole' going within 'inn' is 'insolen'.
'insolen'+'t'='INSOLENT'
(Other definitions for insolent that I've seen before include "Saucy" , "Impudent and disrespectful" , "Extremely fresh" , "Cheeky" , "Pert" .)