Branch of police department that supported hangings? (7)
I believe the answer is:
yardarm
'that supported hangings?' is the definition.
(part of a gallows)
'branch of police department' is the wordplay.
I cannot quite understand how this works, but
'branch' could be 'arm' (synonyms) and 'arm' is present in the answer.
'police' could be 'yard' (Scotland Yard, Metropolitan Police HQ) and 'yard' is found 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 yardarm that I've seen before include "Either end of a spar on a square-rigger's mast" , "From which mutineers once swung?" , "End of spar on ship's mast" , "Tapering end of beam hung on mast" , "part of ship" .)