Disappointed town led astray (3,4)
I believe the answer is:
let down
'disappointed' is the definition.
(I've seen this before)
'town led astray' is the wordplay.
'astray' indicates anagramming the letters.
'town'+'led'='townled'
'townled' with letters rearranged gives 'LET-DOWN'.
(Other definitions for let down that I've seen before include "Aircraft descent" , "Disappoint, betray" , "Leave in the lurch" , "Failed - deflated" , "disillusionment" .)