Turkish commander once more dropping in (3)
I believe the answer is:
aga
'turkish commander' is the definition.
(I've seen this before)
'once more dropping in' is the wordplay.
'once more' becomes 'again' ('again' can be a synonym of 'once more').
'dropping' suggests deleting specific letters.
'again' with 'in' taken out is 'AGA'.
(Other definitions for aga that I've seen before include "Turkish ruler" , "Cooker" , "Oven" , "Muslim title and cooking stove" , "Foreign ruler" .)