A measure that means a bit of a treat for me (5)
I believe the answer is:
metre
'a measure that' is the definition.
'metre' can be an answer for 'a measure' (metre is a kind of measure). I'm not sure about the rest of the definition.
'a bit of a treat for me' is the wordplay.
'a bit of a treat' becomes 'tre' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'tre' put after 'me' is 'METRE'.
'means' acts as a link.
Can you help me to learn more?
(Other definitions for metre that I've seen before include "Characteristic of feet" , "Distance" , "Unit of length in metric system" , "Approx 39 inches" , "Alignment of feet determines such" .)