Ill-mannered pensioner cut short by Sturgeon? (6)
I believe the answer is:
oafish
'ill-mannered' is the definition.
(I've seen this in another clue)
'pensioner cut short by sturgeon?' is the wordplay.
'pensioner' becomes 'OAP' (old age pensioner).
'cut short' means to remove the last letter.
'by' means one lot of letters go next to another.
'sturgeon?' becomes 'fish' (sturgeon is a kind of fish).
'oap' with its last letter removed is 'oa'.
'oa'+'fish'='OAFISH'
(Other definitions for oafish that I've seen before include "Boorish, clumsy" , "In the manner of a clumsy and stupid person" , "Like a lout" , "Loutish" , "Like a boorish person" .)