Naff stuff primarily in gallery? Not so (9)

I believe the answer is:

tasteless

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'naff' is the definition.
I can't judge whether this definition defines the answer.

'stuff primarily in gallery? not so' is the wordplay.
'primarily' indicates taking the first letters.
'in' is an insertion indicator.
'gallery?' becomes 'tate' (Tate Modern, Tate Britain etc).
'not so' becomes 'less' (eg 'not so big' means 'less big').
The initial letter of 'stuff' is 's'.
's' going inside 'tate' is 'taste'.
'taste'+'less'='TASTELESS'

Can you help me to learn more?

(Other definitions for tasteless that I've seen before include "improper" , "Unseemly" , "Insipid - inappropriate - dull" , "Lacking flavour or aesthetic appreciation" , "Vapid" .)

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