Rain's rare in resort, but overdue (2,7)
I believe the answer is:
in arrears
'overdue' is the definition.
(synonyms)
'rain's rare in resort' is the wordplay.
'in resort' indicates an anagram (letters get re-sorted).
'rains'+'rare'='rainsrare'
'rainsrare' is an anagram of 'IN ARREARS'.
'but' acts as a link.
(Other definitions for in arrears that I've seen before include "Late with payments" , "Behindhand (with rent)" , "Rare rains beyond the due time" , "Overdue" , "Behind with payments" .)