Darling daughter always in time for action (1-3)
I believe the answer is:
d-day
'time for action' is the definition.
(I've seen this in another clue)
'darling daughter always in' is the wordplay.
'darling' becomes 'd' (this could be a standard abbreviation I've not previously seen).
'daughter' becomes 'd' (genealogical abbreviation).
'always' becomes 'ay' (archaic term for 'always').
'in' is an insertion indicator.
'd'+'ay'='day'
'd' going into 'day' is 'D-DAY'.
Can you help me to learn more?
(Other definitions for d-day that I've seen before include "June 6, 1944" , "6.6.44" , "World War Two Normandy landings date" , "June six, nineteen fourty-four" , "'June 6th, 1944 (1-3)'" .)