Either a lark or a gull in springtime? (5,4)
I believe the answer is:
april fool
'either a lark' is the definition.
I can't tell whether this definition defines the answer.
'a gull in springtime?' is the wordplay.
I cannot really understand how this works, but
'gull' could be 'fool' (synonyms) and 'fool' is present in the answer.
'springtime?' could be 'april' (I've seen this before) and 'april' is found in the answer.
No letters remain.
This explanation may well be incorrect...
'or' is the link.
Can you help me to learn more?
(Other definitions for april fool that I've seen before include "Victim of hoax in springtime" , "Seasonal victim" , "Spring hoax victim" , "Victim of practical joke at start of a month" , "12 [POISSON DAVRIL]" .)