Order huge necktie to keep performing for fun (6,2,5)
I believe the answer is:
tongue in cheek
'for fun' is the definition.
(something done tongue in cheek is done comedically)
'order huge necktie to keep performing' is the wordplay.
'order' indicates an anagram.
'to keep' means one lot of letters goes inside another.
'performing' becomes 'on' (I've seen this in other clues).
'huge'+'necktie'='hugenecktie'
'hugenecktie' with letters rearranged gives 'tgueincheek'.
'tgueincheek' enclosing 'on' is 'TONGUE-IN-CHEEK'.
(Other definitions for tongue in cheek that I've seen before include "Facetious(ly)" , "In a bantering fashion" , "mouthful of meat" , "With ironical intent" , "Speaking ironically" .)