Mean? No, jolly! (4)

I believe the answer is:

norm

'mean?' is the definition.
(mean is a kind of norm)

'no jolly' is the wordplay.
'jolly' becomes 'rm'.
'no'+'rm'='NORM'

(Other definitions for norm that I've seen before include "Standard regarded as typical" , "'Standard, usual (4)'" , "Most frequent state" , "Rule; average" , "Standard choice" .)

I've seen this clue in The Telegraph.

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