Infrequently (12)
There are a few possibilities for this:
occasionally
'infrequently' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rarely that I've seen before include "Not very often, seldom in fact" , "when hundred-to-one horse wins?" , "Not done or occurring very often" , "Seldom, not frequently" , "once in a blue moon" .)
'infrequently' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for seldom that I've seen before include "Not very often, rarely" , "Alluvium" , "Only occasionally" , "Models (anag)" , "on rare occasions" .)
'infrequently' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for occasionally that I've seen before include "Sometimes" , "At times" , "every now and then" , "From time to time" .)