27 shift across this, oddly (6)
I believe the answer is:
motive
'27' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?
'shift across this oddly' is the wordplay.
'shift' becomes 'move' (I've seen this before).
'across' is an insertion indicator.
'oddly' indicates alternate letters.
The alternate letters of 'this' are 'ti'.
'move' placed around 'ti' is 'MOTIVE'.
Can you help me to learn more?
(Other definitions for motive that I've seen before include "Reason for committing a crime" , "Underlying intention" , "Reason for doing something, perhaps a crime" , "Reason behind an action" , "Ground" .)