When descending on Kansas makes requests (4)
I believe the answer is:
asks
'makes requests' is the definition.
(I've seen this in another clue)
'when descending on kansas' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'descending on' says to put letters next to each other (in a down clue, some letters go on top of others).
'kansas' becomes 'KS' (abbreviation).
'as'+'ks'='ASKS'
(Other definitions for asks that I've seen before include "Invites; enquires" , "Enquires; requests" , "Inquiries" , "Demands (something of someone)" , "Requests information about" .)