The National Front, at the time in question (4)
I believe the answer is:
then
'time in question' is the definition.
The definition and answer can be both related to time as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'the national front at the' is the wordplay.
'front' indicates taking the first letters.
'at' means one lot of letters go next to another (I've seen this in other clues).
The initial letter of 'national' is 'n'.
'n' put after 'the' is 'THEN'.
Can you help me to learn more?
(Other definitions for then that I've seen before include "Consequently" , "At that time; next" , "soon?" , "Afterwards - as a result" , "Once upon a time" .)