Played a trick - it doesn't occur very often (4,3)
I believe the answer is:
leap day
'it doesn't occur very often' is the definition.
'played a trick' is the wordplay.
'trick' is an anagram indicator.
'played'+'a'='playeda'
'playeda' anagrammed gives 'LEAP-DAY'.
(Other definitions for leap day that I've seen before include "29th February" , "short period in an Olympic year?" , "extra 24 hours" , "29 February" .)