Now has a tenant - start to search for keys (6)
I believe the answer is:
islets
'for keys' is the definition.
(I have seen 'small keys' mean 'islets' so perhaps 'keys' could also mean 'islets')
'now has a tenant start to search' is the wordplay.
I cannot really see how this works, but
'has' could be 'lets' (letting is a kind of having) and 'lets' is present in the answer.
The remaining letters 'is' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for islets that I've seen is " small keys".)