Like the veterans who started to back De Gaulle (4)
I believe the answer is:
aged
'de gaulle' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see an association between them that I can't see?
'like the veterans who started to back' is the wordplay.
'like the veterans' becomes 'age' (I can't justify this - if you can you should believe this answer much more).
'who' becomes 'dr' (from TV series Doctor Who).
'started' means to remove the last letter (I've seen 'starts' mean this).
'to back' says to put letters next to each other (some letters go at the back of others).
'dr' with its last letter removed is 'd'.
'age'+'d'='AGED'
Can you help me to learn more?
(Other definitions for aged that I've seen before include "Advanced in years" , "Mature" , "Very old, person or wine" , "well over the hill" , "Antiquated" .)