Crane that is circling hawk (March 1st) (10)
I believe the answer is:
demoiselle
'crane' is the definition.
(demoiselle is a species of crane)
'circling hawk march 1st' is the wordplay.
'circling' is an insertion indicator (circling can mean going around or containing).
'hawk' becomes 'sell' (I've seen this in another clue).
'march' becomes 'demo' (as in a demonstration).
'ist' becomes 'ie' (I am not sure about this - if you are sure you should believe this answer much more).
'demo'+'ie'='demoie'
'sell' placed inside 'demoie' is 'DEMOISELLE'.
'that is' acts as a link.
Can you help me to learn more?
(Another definition for demoiselle that I've seen is " Young woman (archaic)".)