Letters secure cricket ground (9)
I believe the answer is:
'letters' is the definition.
(people who let property)
'secure cricket ground' is the wordplay.
'secure' becomes 'land' (I've seen this before).
'cricket ground' becomes 'lords' (I've seen this before).
(Other definitions for landlords that I've seen before include "People in pubs" , "They lease out properties" , "maybe posted locally?" , "letters" .)