Turn back short old maid (8)
I believe the answer is:
spinster
'old maid' is the definition.
(I know that old maid can be written as spinster)
'turn back short' is the wordplay.
'turn' becomes 'spin' (spin is a kind of turn).
'back' becomes 'stern' (stern means the back of a boat).
'short' means to remove the last letter.
'stern' with its final letter taken off is 'ster'.
'spin'+'ster'='SPINSTER'
(Other definitions for spinster that I've seen before include "woman like Miss Havisham" , "matchless female" , "old maid, perhaps" , "One spurning union activity" , "For example, Miss Havisham" .)