subs. (colloquial).A decline in circumstances; a come-down.
1866. The London Miscellany, 3 March, 57, 3, London Revelations. Bug-hunting (robbing drunken men) was about the best game out, and he added, I dont think thats no little LET-DOWN for a cove as has been tip-topper in his time, and smelt the insides of all the coops in the three kingdoms.