Short trip with short authoritarian old maid (8)
I believe the answer is:
spinster
'old maid' is the definition.
(synonyms)
'short trip with short authoritarian' is the wordplay.
'short trip' becomes 'spin' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'short' means to remove the last letter.
'authoritarian' becomes 'stern' (I've seen this before).
'stern' with its last letter removed is 'ster'.
'spin'+'ster'='SPINSTER'
(Other definitions for spinster that I've seen before include "For example, Miss Havisham" , "She never married" , "One spurning union activity" , "woman like Miss Havisham" , "Elderly unmarried woman" .)