Letters descend on cricket's HQ (9)
I believe the answer is:
landlords
'letters' is the definition.
(people who let property)
'descend on cricket's hq' is the wordplay.
'descend' becomes 'land'.
'on' means one lot of letters go next to another.
'cricket's hq' becomes 'Lords' (British cricket ground).
'land'+'lords'='LANDLORDS'
(Other definitions for landlords that I've seen before include "letters" , "They lease out properties" , "People in pubs" , "maybe posted locally?" .)