He's in the dock to wear down old soldiers preposterously (9)
I believe the answer is:
stevedore
'he's in the dock to wear down old soldiers preposterously' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he's in the dock to wear down old soldiers' is the wordplay.
I cannot quite understand how this works, but
'down' could be 'd' and 'd' is located in the answer.
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is found in the answer.
'soldiers' could be 're' (Royal Engineers) and 're' is found within the answer.
'he' could be 'steve' and 'steve' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stevedore that I've seen before include "One is employed at a dock to load and unload ships" , "Worker who loads and unloads ships" , "Dock-worker loads and unloads ships" , "Unloader of shipping vessels" , "Docker" .)