Means of entry during rental period (5)
I believe the answer is:
inlet
'means of entry' is the definition.
(I've seen this before)
'during rental period' is the wordplay.
'during' becomes 'in' (I've seen this in other clues).
'rental period' becomes 'let' (the period during which a property is let).
'in'+'let'='INLET'
(Other definitions for inlet that I've seen before include "Fjord" , "Fiord" , "A small creek or cove" , "Opening - passage" , "Entry; arm of the sea" .)