Nuisance also seen in fair (2-3-2)
I believe the answer is:
so-and-so
'nuisance' is the definition.
'also seen in fair' is the wordplay.
'also' becomes 'and' (I've seen this before).
'seen in' means one lot of letters goes inside another.
'fair' becomes 'soso' (I've seen this in another clue).
'and' put within 'soso' is 'SO-AND-SO'.
(Other definitions for so-and-so that I've seen before include "What's-his-name; a nuisance" , "Thus and thus - an unpleasant person" , "Difficult person - nobody in particular" , "Someone or other - unpleasant person!" , "Right little rascal!" .)