That of one in a position of dignity? (5)
I believe the answer is:
poise
'dignity?' is the definition.
(I've seen this in another clue)
'that of one in a position' is the wordplay.
'that of one' becomes 'i' (I've seen this in other clues).
'in' indicates putting letters inside.
'a position' becomes 'pose' (I've seen this before).
'i' inserted within 'pose' is 'POISE'.
'of' acts as a link.
(Other definitions for poise that I've seen before include "Balance; composure" , "Coolness and composure under strain" , "Elegance" , "Dignified and self-assured manner" , "Physical balance" .)