You are initially baffled by fresh alarm (7)
I believe the answer is:
perturb
'alarm' is the definition.
(thesaurus)
'you are initially baffled by fresh' is the wordplay.
'you are' becomes 'ur' (text or internet abbreviation).
'initially' says to take the initial letters.
'by' is a charade indicator (letters next to each other).
'fresh' becomes 'pert' (I've seen this before).
The first letter of 'baffled' is 'b'.
'ur'+'b'='urb'
'urb' put after 'pert' is 'PERTURB'.
(Other definitions for perturb that I've seen before include "Make unsettled" , "Opera star" , "Ruffle the composure (of)" , "Disturb the composure of" , "Worry" .)